Mens Rea: An Overview of State-of-Mind Requirements for Federal Criminal Offenses

June 30, 2021 – July 7, 2021 R46836

Mens Rea: An Overview of State-of-Mind
July 7, 2021
Requirements for Federal Criminal Offenses
Michael A. Foster
The concept of mens rea, or a “guilty mind,” reflects the idea that a crime generally must consist
Legislative Attorney
of not only a proscribed act but also a “mental element” sufficient to warrant punishment. Three

questions regularly arise with respect to the mental state required for a given federal crime: (1)
whether the statute establishing the crime contains a mental-state requirement, or requirements, at

all; (2) if the statute does contain mental-state requirements, which elements of the offense must
meet which requirements; and (3) what the mental-state requirements mean. Under federal law, determining the mental state
required for commission of a crime necessitates an examination of congressional intent.
Congressional intent can be difficult to discern given that federal criminal statutory law (largely codified at Title 18) contains
no uniform mens rea standards or generally applicable definitions of mental-state terms. Because federal statutory law lacks
general rules for assessing and applying mens rea terms and requirements across criminal statutes, courts have applied canons
of statutory interpretation and developed presumptions specific to mens rea when the state of mind requirement for a federal
offense is unclear. For example, when a criminal statute is silent on the question of what mental state is required, courts will
ordinarily apply a presumption in favor of scienter. The presumption counsels that typically some indication is required that
Congress intended to dispense with mens rea as an element of a crime, and simply omitting a mens rea term from the
statutory language will not be considered adequate evidence of such intent. Assuming the presumption of mens rea applies
and calls for a mental-state requirement to be read into a statute that does not expressly contain one, the question becomes
what kind of mental state is required. In this respect, the Supreme Court has said that the presumption requires “only that
mens rea which is necessary to separate wrongful conduct from ‘otherwise innocent conduct’”—typically, at least knowledge
of certain elements of the offense at issue.
With respect to which elements of a crime must meet a given mens rea requirement, the Supreme Court has stated that the
presumption in favor of scienter applies to “each of the statutory elements that criminalize otherwise innocent conduct,”
though such a distributive approach emphasizing a distinction between elements that make conduct criminal and those that do
not can sometimes be difficult to apply in practice. Finally, regarding what specific mental-state requirements mean, federal
law uses dozens of different mens rea terms that are frequently undefined. As such, reference to judicial precedent construing
the provision at issue is often required to understand what mental state is required for a particular federal crime. Even so,
federal mens rea requirements largely fall into loose categories that may include (1) an awareness of, or conscious purpose to
bring about, conduct, a circumstance, or a result that is a required element of the offense (commonly represented by terms
such as “intent,” “knowledge,” or “willfulness,” among others), or (2) an awareness and disregard of a substantial risk of
harm or failure to perceive a substantial risk of harm when a reasonable person would have perceived it (commonly
represented by the terms “recklessness” and “negligence,” respectively).
A class of “public welfare” or “regulatory” offenses may actually require no mens rea for their commission at all. For this
class of offenses, rather than applying the presumption in favor of scienter, statutory silence is treated as imposing “strict
criminal liability” in the sense that one need not have at least knowledge of the facts that make one’s conduct illegal.
Ultimately, several factors may be relevant to a court’s determination of whether a particular criminal statute imposes strict
liability, including the nature of the statute and the particular activity or item regulated, the purpose of the criminal
prohibition (i.e., punishment of wrongdoing versus protection of the public), the degree to which a defendant will be in a
position to ascertain the relevant facts, and the severity of the penalties.
In the past, Congress has considered legislation that would have established default mens rea requirements and application
rules in the absence of clear standards in the offense text, and at least one bill (S. 739) has been introduced to this effect in the
117th Congress. Among other things, such legislation would impose standards of either knowledge or willfulness on many
offense elements and would require that mens rea terms provided in the text should ordinarily apply to each offense element,
with exceptions. Proponents of such efforts argue that strict-liability offenses and offenses with weak mental-state
requirements fail to provide fair notice and represent part of a broader trend of federal over-criminalization. Opponents assert
that applying blanket mens rea requirements to existing offenses could permit corporate wrongdoers to evade prosecution and
produce unintended consequences. Ultimately, comprehensive mens rea legislation has not become law as of this writing.
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Introduction
To say that the legal principle actus non facit reum nisi mens sit rea1 is longstanding would be a
considerable understatement. According to some legal scholars, the phrase, which means “the act
is not culpable unless the mind is guilty,” has been in use for “at least approximately one
thousand years.”2 Embodied in the phrase is the “universal and persistent” notion that “an injury
can amount to a crime only when inflicted by intention.”3 In contemporary American law, the
concept of mens rea, or a “guilty mind,” reflects this idea that a crime generally must consist of
not only a “harmful act” but also a “mental element” or criminal intent sufficient to justify
punishment.4
A world of complexity belies the seeming simplicity of the principle that a crime requires a guilty
mind. To start, “mental element,” “guilty mind,” or “state of mind”5 are somewhat imprecise
terms, as they may be used to refer to “matters that are not really mental at all” (for instance,
crimes that only require a mens rea of negligence).6 Additionally, courts face persistent issues in
interpreting mens rea standards like “knowledge,” “willfulness,” and “intent” and determining
which elements in particular crimes must meet these standards.7

1 An alternative phrasing that is sometimes used is actus reus non facit reum nisi mens sit rea. Compare United States
v. Bates, 96 F.3d 964, 967 (7th Cir. 1996), with Craig A. Stern, The Heart of Mens Rea and the Insanity of
Psychopaths, 42 CAP. U. L. REV. 619, 627 n.58 (2014).
2 Matthew R. Ginther & Francis X. Shen, et al., Decoding Guilty Minds: How Jurors Attribute Knowledge and Guilt,
71 VAND. L. REV. 241, 245 n.10 (2018); see also Francis Bowes Sayre, Mens Rea, 45 HARV. L. REV. 974, 974 (1932)
(stating that the phrase has been used “[f]or hundreds of years . . . with unbroken cadence”).
3 Morissette v. United States, 342 U.S. 246, 250 (1952).
4 Id. at 250-51. This principle addresses broader notions of the purposes of criminal law and its effectiveness in
deterring, reforming, and/or punishing, i.e., what sorts of behaviors are justly proscribed and can reasonably be
expected to be curtailed by the threat of criminal penalties. See, e.g., id. (noting that the concept of a mental element in
criminal law “is almost as instinctive as the child’s familiar exculpatory ‘But I didn’t mean to,’ and has afforded the
rational basis for a . . . substitution of deterrence and reformation in place of retaliation and vengeance as the
motivation for public prosecution”); Stephen J. Morse, Inevitable Mens Rea, 27 HARV. J.L. & PUB. POL’Y 51, 61 (2003)
(“If the criminal law operates by guiding the conscious actions of persons capable of understanding the rules and
rationally applying them, it would be unfair and thus unjustified to punish and to inflict pain intentionally on those who
did not act intentionally or who were incapable of the minimum degree of rationality required for normatively
acceptable cooperative interaction.”).
5 Various terms are used in judicial opinions and legal scholarship to describe the mental component of a crime,
including mens rea, state of mind, mental state, and scienter. This report uses such terms interchangeably. As noted
below, the Model Penal Code treats the concept of a crime’s mental component under the rubric of “culpability.” See
infra notes 42-71 and accompanying text.
6 WAYNE R. LAFAVE, SUBSTANTIVE CRIMINAL LAW § 5.1 (3d ed. 2017); see Criminal Negligence, BLACK’S LAW
DICTIONARY (11th ed. 2019) (defining criminal negligence as, among other things, an “objectively assessed mental
state of an actor who should know” that there is a certain degree of risk in a prohibited action). However, criminal
negligence is not common in the context of federal criminal law. See 1A KEVIN F. O’MALLEY, JAY E. GRENIG, &
WILLIAM C. LEE, FEDERAL JURY PRACTICE & INSTRUCTIONS § 17:01 (6th ed. 2006) (indicating that concepts of
recklessness, negligence, and strict liability have “little relevance in federal criminal law”); Elonis v. United States, 135
S. Ct. 2001, 2011 (2015) (“[W]e have long been reluctant to infer that a negligence standard was intended in criminal
statutes.” (citation and internal quotation marks omitted)); but see, e.g., 33 U.S.C. § 1319(c) (establishing criminal
penalties for negligent violations of certain pollutant discharge limitations, among other things).
7 E.g., Robert Batey, Judicial Exploitation of Mens Rea Confusion, at Common Law and Under the Model Penal Code,
18 GA. ST. L. REV. 341, 341-42 (2001) (referring to “infinite shades of meaning” among common-law mens rea
standards and “important fundamental mens rea questions that still have no clear answers”); United States v. Bailey,
444 U.S. 394, 403 (1980) (“Few areas of criminal law pose more difficulty than the proper definition of the mens rea
required for any particular crime.”); United States v. Marshall, 753 F.3d 341, 345 (1st Cir. 2014) (“The statutory term
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Moreover, though courts have pronounced in sweeping language the paramount importance of
imposing criminal punishment only on those who are mentally culpable, a class of so-called
“regulatory” or “public welfare” offenses are said to be “strict liability” crimes in that they
require no mens rea for their commission at all.8
One resource that has played a significant role in the development and clarification of certain
mens rea principles is the Model Penal Code (MPC).9 The MPC is a major work of legal
scholarship first produced in 1962 that was intended to establish a comprehensive model statute
that American jurisdictions could use to revise their criminal codes.10 Many states have, in whole
or part, supplanted “confused, vague, and inconsistent” approaches to mental states drawn from
the common law with the more systematic approach to state-of-mind requirements found in the
MPC’s “culpability” provisions.11 Federal courts also have looked to MPC principles for
guidance in interpreting federal law,12 notwithstanding the fact that federal criminal statutory law
(largely codified at Title 18) contains no uniform mens rea standards or generally applicable
definitions of mental-state terms.13 Given that federal statutory law lacks such consistent rules for
assessing and applying mens rea terms and requirements across criminal statutes, courts have had
to use canons of statutory interpretation14 and adopt certain mens rea-specific presumptions when
the state of mind required for a particular federal offense is unclear.15
In light of the ad hoc nature of state-of-mind requirements under federal law, Congress has shown
interest for decades in establishing more systematized mens rea standards and application rules.16
Because the issue is one of perennial interest to Congress, this report provides an overview of
mens rea requirements for federal crimes.17 The report first sketches the common-law background

‘willfully’ is a chameleon, what the Supreme Court has called ‘a word of many meanings whose construction is often
dependent on the context in which it appears.’” (citation omitted)).
8 See infra § “Whether Mens Rea is Required”; Morissette, 342 U.S. at 250, 252-255 (stating that the requirement of a
“mental element” for commission of a crime is “no provincial or transient notion” but recognizing offenses “of another
character” which require no such element and “consist only of forbidden acts or omissions”).
9 See David M. Treiman, Recklessness and the Model Penal Code, 9 AM. J. CRIM. L. 281, 284-85 (1981) (describing
MPC as “model for” reforming common-law mens rea principles reflected in statutes of the time).
10 See id.
11 Id. (indicating that as of 1981, nearly two-thirds of states had revised their criminal codes based on the MPC, and
many revisions included the MPC’s section on culpability); see Paul H. Robinson & Markus D. Dubber, The American
Model Penal Code: A Brief Overview, 10 NEW CRIM. L. REV. 319, 326 (2007) (identifying “thirty-four [state]
enactments [that] were influenced in some part by the Model Penal Code”).
12 E.g., Bailey, 444 U.S. at 406 (looking to “[p]rinciples derived from common law as well as precepts suggested by
the” MPC to discern level of culpability); Voisine v. United States, 136 S. Ct. 2272, 2278 (2016) (citing MPC
definition of “reckless” as “the dominant formulation”).
13 Geraldine Szott Moohr, Playing with the Rules: An Effort to Strengthen the Mens Rea Standards of Federal Criminal
Laws, 7 J. L. ECON. & POL’Y 685, 692 (2011) (“The United States Code does not define mens rea terms or provide
interpretive guidelines. Instead, each federal criminal law specifies its own mens rea element, making it possible for
legislators to select from a wealth of common law terms.”).
14 For more information on statutory interpretation as a general matter, see CRS Report R45153, Statutory
Interpretation: Theories, Tools, and Trends, by Valerie C. Brannon.
15 E.g., United States v. X-Citement Video, Inc., 513 U.S. 64, 72 (1994) (acknowledging a “presumption in favor of a
scienter requirement” that “should apply to each of the statutory elements that criminalize otherwise innocent
conduct”).
16 E.g., Mens Rea Reform Act of 2018, S. 3118, 115th Cong. (2018); Criminal Code Reform Act of 1977, S. 1437, 95th
Cong. ch. 3 (as passed by Senate, Jan. 30, 1978). For further discussion, see infra notes Error! Bookmark not d
efined.-Error! Bookmark not defined. and accompanying text.
17 This report limits its focus to federal mens rea requirements for purposes of criminal liability and thus largely does
not address mental-state issues that may arise at sentencing or under the U.S. Sentencing Guidelines. See, e.g., United
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of the concept of mens rea, summarizes the MPC’s innovations on the subject, and then explores
mens rea standards and interpretive issues in federal statutes and caselaw.18 The report concludes
with a brief discussion of recent proposals that would impact federal mens rea requirements and
some of the arguments in favor of and in opposition to such proposals.
Background
A crime traditionally has been understood to consist of the concurrence of both a proscribed act
(the actus reus) and a “guilty mind” (or mens rea).19 The concept of a mental element—mens rea,
scienter, state of mind, criminal intent, or an equivalent term—being necessary for a prohibited
act to be sufficiently blameworthy to justify criminal punishment has endured for hundreds of
years, if not longer.20 In its early form at English common law, at least according to some
scholars, mens rea embodied the notion of an intent to do an act with an “evil motive.”21 This
“original notion . . . was gradually transformed by a centuries-long process that attempted to
identify specific states of mind required for the commission of particular offenses.”22 The concept
of a guilty mind as a necessary component of crime “took deep and early root in American soil,”23
but by the middle of the twentieth century, the common-law development of particular state-of-
mind requirements on a crime-by-crime basis (and their inconsistent codification, in whole or in
part, in state criminal codes) led to considerable disarray and confusion.24

States v. Prophet, __F.3d__, No. 18-3776, 2021 WL 800384, at *2 (3d Cir. Mar. 3, 2021) (noting circuit split regarding
whether earlier version of Guideline enhancement required finding of mens rea).
18 Because, as already described, federal mens rea standards are statute-specific and non-uniform, it would be
impossible to comprehensively address the state-of-mind requirements for federal crimes in a general way. Thus, this
report seeks only to exemplify the variation in federal criminal law by exploring the requirements of a few
representative statutes.
19 LAFAVE, supra note 6, § 5.1.
20 See Martin R. Gardner, The Mens Rea Enigma: Observations on the Role of Motive in the Criminal Law Past and
Present, 1993 UTAH L. REV. 635, 642 (1993) (tracing origins of a mental element in crime to “the earliest known legal
systems” but noting that “systematic mens rea requirements” did not exist in Anglo-Saxon law “until at least the
thirteenth century”).
21 Id. at 654-67.
22 Id. at 667. Motive is often now recognized to be analytically distinct from mens rea. United States v. Safehouse, 985
F.3d 225, 238 (3d Cir. 2021) (“[M]otive is distinct from mens rea. A defendant can be guilty even if he has the best of
motives.”); Gardner, supra note 20, at 694 (“The modern practice . . . largely abandons the evil motive tradition at the
offense definition level by defining the mens rea required for each crime descriptively in terms of particular states of
mind.”). The relationship between the two can still sometimes creates conceptual difficulty in particular contexts,
however. See, e.g., United States v. Ali, 870 F. Supp. 2d 10, 20 (D.D.C. 2012) (“Court decisions, treatises, and law
reviews are rife with debates about the relationship between specific intent and motive, and the relevance (if any) of the
latter in a criminal case.”). Motive may also be an express element of particular crimes, such as hate crimes, e.g., 18
U.S.C. § 249(a) (prohibiting certain acts “because of the actual or perceived race, color, religion, or national origin of
any person,” among other things), and, depending on one’s definition, may also be considered a component of certain
defenses to criminal liability. See, e.g., Rosemond v. United States, 572 U.S. 65, 89 (2014) (Alito, J., concurring in part
and dissenting in part) (“Unsurprisingly, our cases have recognized that a lawful motive (such as necessity, duress, or
self-defense) is consistent with the mens rea necessary to satisfy a requirement of intent.”); Gardner, supra note 20, at
694-95 (explaining that the law “affords excuses in certain situations, even though offenders act with the specific state
of mind required for the crime but either lack, or lack the capacity to form, the evil motive essential for moral blame”).
23 Morissette v. United States, 342 U.S. 246, 252 (1952).
24 Id. at 252 (“The unanimity with which [courts] have adhered to the central thought that wrongdoing must be
conscious to be criminal is emphasized by the variety, disparity and confusion of their definitions of the requisite but
elusive mental element.”); Treiman, supra note 9, at 284 (“Before 1960, most states had criminal codes that were little
more than statutory versions of the common law . . . . Each crime was defined in virtual isolation from others and
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This confusion is perhaps best reflected in the development of the concepts of “general intent”
and “specific intent” as a shorthand way to describe the mens rea classifications of common-law
crimes. At a high level, many such offenses—for example, murder, battery, and larceny—can be
characterized as either “specific intent” or “general intent” crimes.25 In one formulation, “specific
intent” denotes an intent to “achieve some additional consequence” or “commit some further act”
beyond the “commission of the proscribed act.”26 For example, larceny likely would be
considered a specific intent crime, as it often requires obtaining control over the property of
another (the proscribed act) with the intent “to deprive the owner of the stolen property
permanently.”27 By contrast, in the words of one federal appellate court, “a general intent crime
requires only that the act was volitional (as opposed to accidental), and the defendant’s state of
mind is not otherwise relevant.”28 For instance, battery at common law “consisted of the unlawful
application of force to the person of another, including an offensive touching.”29 This crime
would be considered a general intent crime, because it does not “require any specific intent either
to injure or to touch offensively, but rather only a more general intent to commit the unlawful act”
of applying force.30
Though the examples of larceny and battery might suggest relative clarity, delineation between
“specific intent” and “general intent” crimes in fact can be problematic in several respects. For
one thing, disagreement has abounded over time as to the proper meaning and usage of the two
terms. As explained by the Supreme Court:
Sometimes “general intent” is used in the same way as “criminal intent” to mean the
general notion of mens rea, while “specific intent” is taken to mean the mental state
required for a particular crime. Or, “general intent” may be used to encompass all forms of
the mental state requirement, while “specific intent” is limited to the one mental state of
intent. Another possibility is that “general intent” will be used to characterize an intent to
do something on an undetermined occasion, and “specific intent” to denote an intent to do
that thing at a particular time and place.31
Additionally, even classifying a crime as requiring either specific or general intent might not
necessarily serve to elucidate the requisite mental state in a meaningful way. As one scholar has
framed it, the concepts of general and specific intent do not themselves “describe culpable mental
states” but merely “describe the relationship between an offense’s mental elements and its

consequently, the meaning of terms would vary from crime to crime, with no attempt at consistent definition . . . .”).
25 United States v. Bailey, 444 U.S. 394, 403 (1980); Batey, supra note 7, at 343. As discussed in more detail infra, a
third category of so-called regulatory or strict-liability offenses requires no culpable mental state at all. See Morissette,
342 U.S. at 252-53 (noting offenses “with very different antecedents and origins” that “depend on no mental element
but consist only of forbidden acts or omissions”).
26 Eric A. Johnson, Understanding General and Specific Intent: Eight Things I Know for Sure, 13 OHIO ST. J. CRIM. L.
521, 525, 527 (2016); see also United States v. Lamott, 831 F.3d 1153, 1156 (9th Cir. 2016) (“In a crime requiring
‘specific intent,’ the government must prove that the defendant subjectively intended or desired the proscribed act or
result.”).
27 Johnson, supra note 26, at 525.
28 Lamott, 831 F.3d at 1156. Defining general intent solely in terms of volition is of dubious usefulness, as any crime
proscribing an affirmative act requires that the act be voluntary. See LAFAVE, supra note 6, § 6.1(c) (“At all events, it is
clear that criminal liability requires that the activity in question be voluntary.”).
29 United States v. Delis, 558 F.3d 177, 180 (2d Cir. 2009).
30 Id.
31 United States v. Bailey, 444 U.S. 394, 403 (1980) (quoting WAYNE R. LAFAVE & AUSTIN W. SCOTT, JR., HANDBOOK
ON CRIMINAL LAW 201-02 (1972)).
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physical elements.”32 A crime might be considered a “general intent” crime, in other words,
because it does not require a specific mental state with respect to some consequence or result
beyond the proscribed act (as in the battery example), but this does little to clarify the meaning of
the mens rea requirement that the crime does have. Though the definition of “general intent”
given above distinguishes only between volition and accident, the concept of intentionality has
long been “slice[d] . . . more finely than accident versus non-accident.”33 In fact, a crime might
incorporate the notion of a volitional act that brings about an unintended (read: accidental) result
where the actor is highly careless in failing to appreciate the risk that a reasonable person would
appreciate.34 This kind of crime does not fit comfortably in either the general or the specific intent
bucket, nor does a crime that requires conscious disregard of a known risk.35
Exacerbating these definitional problems at common law was the proliferation of different mens
rea terms that often provided little clarity as to what sort of mental state was actually required.
“Terms such as willfully, corruptly, maliciously, feloniously, wrongfully, unlawfully, wantonly,
intentionally, purposely, with criminal negligence, and culpably” were all used (among others),
sometimes “to describe what was probably the same mental state,” sometimes to describe
different mental states, and often without “any further definition.”36 The result was “seemingly
infinite shades of meaning along [a] continuum upon which” the concepts of specific and general
intent resided.37 It was in the context of this “variety, disparity, and confusion of [judicial]
definitions of the requisite but elusive mental element”38 that the drafters of the MPC sought to
establish “relatively clear definitions of mental requirements and relatively straightforward rules
regarding how to read these requirements into criminal statutes”39 through what it termed general
“culpability” rules.40 Because the MPC approach has had a significant impact on the development
and understanding of the mental element of crime in general,41 this report provides a brief
overview of the MPC’s culpability provisions.
Model Penal Code Approach
As noted above, the MPC was intended to be used as a model for criminal code reform across
jurisdictions.42 It has proved to be extremely influential, with many states revising their codes in

32 Johnson, supra note 26, at 522-23.
33 Francis X. Shen & Morris B. Hoffman, et al., Sorting Guilty Minds, 86 N.Y.U. L. REV. 1306, 1310 (2011).
34 Id. at 1311.
35 See Johnson, supra note 26, at 532-36 (noting court disagreement and arguing that such crimes should be considered
general intent crimes).
36 Treiman, supra note 9, at 284.
37 Batey, supra note 7, at 341.
38 Morissette v. United States, 342 U.S. 246, 252 (1952).
39 Batey, supra note 7, at 401; see also Ronald L. Gainer, The Culpability Provisions of the Model Penal Code, 19
RUTGERS L.J. 575, 579 (1988) (explaining that the MPC drafters “were required to resolve an approach to culpability”
and “appeared to recognize that the fundamental need was clarity”).
40 MODEL PENAL CODE § 2.02 (1985).
41 See, e.g., Gainer, supra note 39, at 579 (describing MPC approach as “the now classic approach to culpability that
few of us could imagine doing without”); Paul H. Robinson, A Brief History of Distinctions in Criminal Culpability, 31
HASTINGS L.J. 815, 816 & n.7 (1980) (recognizing that around seventy percent of states undertaking code revisions
adopted a mental-state system “essentially identical” to the MPC, and even those that did not were “significantly
influenced” by it).
42 Robinson & Dubber, supra note 11, at 323; see also Sanford H. Kadish, Fifty Years of Criminal Law: An
Opinionated Review, 87 CAL. L. REV. 943, 947-48 (1999). The MPC was reissued with Commentaries in 1980 and
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light of the MPC’s principles and with some federal courts looking to those principles in
construing federal law.43
The MPC’s culpability provisions are found in Article 2 of Part I, principally Section 2.02 and
surrounding sections. One of these provisions’ core achievements is in “reduc[ing] nearly eighty
miscellaneous culpability terms to five carefully defined levels.”44 These levels have become a
prevalent, if not the predominant, prism through which courts view state-of-mind distinctions.45
The five levels of culpability are: (1) purpose; (2) knowledge; (3) recklessness; (4) negligence;
and (5) strict liability.46 The MPC also clarifies the relationship between these different
culpability levels and the offense elements to which they apply by dividing elements into three
categories: (1) conduct, (2) attendant circumstances, and (3) results.47 The element categories are
not defined, but an example of conduct and circumstance elements might involve a crime of
having sexual intercourse with a minor, with intercourse being the conduct element and the age of
the victim being the circumstance element.48 An example of a result element would be engaging
in conduct that causes the death of another human being, with death being the proscribed result.49
Each culpability level in the MPC is defined in relation to each kind of objective offense
element.50 The table below reflects the definitions of the MPC’s culpability levels for the three
element categories:

1985.
43 See supra notes 11-12 and accompanying text; Paul H. Robinson, The Rise and Fall and Resurrection of American
Criminal Codes, 53 LOUISVILLE L. REV. 173, 173 (2015).
44 Robinson, Brief History, supra note 41, at 815.
45 Id. at 816.
46 MODEL PENAL CODE §§ 2.02(2)(a)-(d), 2.05 (1985).
47 See generally id. § 2.02. The MPC defines the term “element of an offense” as such conduct, circumstance, or result
of conduct as “is included in the description of the forbidden conduct in the definition of the offense,” establishes the
requisite culpability, negates an excuse, justification, or a statute of limitations defense, or establishes jurisdiction or
venue. Id. § 1.13(9).
48 Paul H. Robinson, Reforming the Federal Criminal Code: A Top Ten List, 1 BUFF. CRIM. L. REV. 225, 235 (1997).
49 Id.
50 MODEL PENAL CODE § 2.02 (1985); e.g., id. § 2.02(2)(a) (“Purposely. A person acts purposely with respect to a
material element when (i) if the element involves the nature of his conduct or a result thereof, it is his conscious object
to engage in conduct of that nature or to cause such a result; and (ii) if the element involves the attendant
circumstances, he is aware of the existence of such circumstances or he believes or hopes that they exist.”) (emphasis
added).
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Table 1. MPC Culpability Levels
Culpability Level
Conduct
Circumstance
Result
Purposely
Conscious object to
Aware of the
Conscious object to
engage in conduct of
existence of such
cause such a result51
that nature
circumstances or
believes or hopes that
they exist
Knowingly
Aware that conduct is Aware of at least a
Aware that it is
of that nature
high probability that
practically certain
such circumstances
that conduct will
exist, unless actor
cause such a result
actually believes they
do not exist52
Recklessly
None53
Consciously
Consciously
disregards a
disregards a
substantial and
substantial and
unjustifiable risk that unjustifiable risk that
the material element
the material element
exists
will result from
conduct54
Negligently
None
Should be aware of a Should be aware of a
substantial and
substantial and
unjustifiable risk that unjustifiable risk that
the material element
the material element
exists
will result from
conduct55
Strict Liability
None
None
None

51 A separate provision establishes that a “conditional” purpose satisfies the requirement of purpose “unless the
condition negatives the harm or evil sought to be prevented by the law defining the offense.” Id. § 2.02(6).This
provision encompasses a situation where, for instance, an actor might be guilty of larceny (which requires a purpose to
deprive the owner permanently of property) if the actor takes property intending to keep it unless the actor wins the
lottery. In this situation, though the purpose is conditional, the condition does not “negative[] the harm or evil sought to
be prevented,” but if the actor takes the property intending to keep it only if it turns out to actually be his, the harm or
evil arguably would be negated. See LAFAVE, supra note 6, § 5.2(d).
52 This definition, which is actually a product of two separate provisions of Section 2.02, encompasses a formulation of
the common-law “willful blindness” doctrine, under which “persons who know enough to blind themselves to direct
proof of critical facts in effect have actual knowledge of those facts” for mens rea purposes. Global-Tech Appliances,
Inc. v. SEB S.A., 563 U.S. 754, 766 (2011).
53 The MPC does not expressly define recklessness or negligence with respect to conduct, though commentators have
different perspectives on the significance of the omission. Some commentators have posited that the drafters may have
thought that recklessness or negligence as to conduct is not likely to arise, while others have suggested that the
minimum culpability that applies with respect to conduct is knowledge. For further discussion of this issue, see Paul H.
Robinson & Jane A. Grall, Elements Analysis in Defining Criminal Liability: The Model Penal Code and Beyond, 35
STAN. L. REV. 681, 710-12 (1983).
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Source: American Law Institute, Model Penal Code, Section 2.02.
As the table reflects, the MPC’s culpability levels may be viewed in a kind of descending order
of intentionality. “Purposely” generally requires an element to be the actor’s “conscious object,”
“knowingly” requires the actor’s awareness to a practical certainty or of a high probability
(regardless of what the actor desires or has as their object), “recklessly” requires the actor’s
awareness of a substantial risk, and “negligence” requires no awareness at all but merely that the
actor objectively should have been aware of a substantial risk. For a limited category of strict
liability offenses, the mental state of the actor is irrelevant.56 These definitions represent an effort
to cut through the confusing morass of mens rea terms that had existed up to that point.57 The
categorization of offense elements and the implicit recognition that the requisite mens rea might
be different and should be analyzed separately with respect to each offense element also reflects a
shift away from a prior notion that “each offense has one state of mind requirement,” i.e., that
criminal offenses may be classified simply as “general intent” or “specific intent” rather than
specifying what state of mind is actually required for which components of the crime.58
Beyond the definitions of mental-state requirements and the move towards mens rea element
analysis with respect to those requirements, the MPC establishes certain general principles of
interpretation that apply in assessing the mental state or states required for a particular offense.59
Most notably, the MPC creates a baseline culpability standard for any material element60 that does
not explicitly contain one—Section 2.02(3) states that unless otherwise provided, “[w]hen the
culpability sufficient to establish a material element of an offense is not prescribed by law,” the
element is established if the person acts at least recklessly.61 Coupled with this default rule is a
rule that if an offense prescribes the culpability level sufficient for commission of the offense
without specifying which elements of the offense carry that specific culpability requirement, the
requirement applies to all material elements “unless a contrary purpose plainly appears.”62 For
example, for an offense of knowingly killing a “house pigeon,” the prosecution would have to
prove that the actor knowingly killed and that he knew what he killed was a house pigeon, unless

54 For recklessness in general, “[t]he risk must be of such a nature and degree that, considering the nature and purpose
of the actor's conduct and the circumstances known to him, its disregard involves a gross deviation from the standard of
conduct that a law-abiding person would observe in the actor's situation.” MODEL PENAL CODE § 2.02(2)(c) (1985).
55 For negligence in general, “[t]he risk must be of such a nature and degree that the actor's failure to perceive it,
considering the nature and purpose of his conduct and the circumstances known to him, involves a gross deviation from
the standard of care that a reasonable person would observe in the actor's situation.” Id. § 2.02(2)(d).
56 Id. § 2.02.
57 See, e.g., Robinson & Grall, supra note 53, at 692-93 (noting that Section 2.02 “clarifies mens rea analysis” by,
among other things, “narrow[ing]” the “eighty or so culpability terms” that existed previously).
58 Id. at 688.
59 E.g., MODEL PENAL CODE §§ 2.02-.06 (1985).
60 The MPC defines a “material element” as an element that does not relate to basic matters such as the statute of
limitations, jurisdiction, venue, or other matters unconnected with “the harm or evil . . . sought to be prevented by the
law defining the offense” or a justification or excuse for the proscribed conduct. Id. § 1.13(10).
61 Id. § 2.02(3). An explanatory note states that “[t]here is a rough correspondence between this provision and the
common law requirement of ‘general intent.’” Id. § 2.02 explanatory note. The drafters, by omitting “negligence” and
referencing general intent, seemed to indicate that crimes without an explicit mens rea requirement would maintain a
common-law conception requiring at least some conscious awareness of relevant information, as distinct from mere
accident. See supra notes 28-35 and accompanying text.
62 Id. § 2.02(4).
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the text of the law in question “plainly” reflected that knowledge of the type of pigeon should not
be required.63
The MPC additionally provides a number of rules on other points of law that may relate to
mental-state requirements, such as the mens rea for inchoate crimes and certain defenses.64 This
report addresses the MPC approach to these topics as a point of comparison with approaches
under federal law in subsequent sections.65
In the decades since the MPC’s initial development, a substantial body of legal scholarship has
offered critiques of, and potential refinements to, its culpability provisions.66 For instance, some
commentators have taken issue with the “narrow distinction” between knowledge and
recklessness with respect to a circumstance, which appears to turn on the murky question of what
is highly probable versus a “substantial risk.”67 Others have noted the conflict and inconsistency
that can arise in applying the rule that recklessness is the default when culpability is undefined
over the rule that a culpability requirement attached to one material element normally attaches to
all.68 Nonetheless, legal scholars appear largely to prefer the MPC’s approach to mental states
over the disarray of the common law, asserting that the MPC’s culpability provisions are a
“tremendous advance.”69 Many U.S. jurisdictions also have either adopted a number of the
provisions or been influenced by them,70 and the Supreme Court has also looked to the MPC as a
“source of guidance” in construing mens rea requirements in federal criminal statutes.71 What is
notable about federal law, however, is that the MPC’s culpability provisions have not been
codified or adopted on a broad scale. Instead, federal law largely embodies an ad hoc approach,
which this report now examines in more detail.
Federal Mens Rea Requirements
In 1966, Congress created the National Commission on Reform of Federal Criminal Laws, which
was given a broad mandate to “review and study . . . the statutory and case law of the United
States . . . for the purpose of formulating and recommending to the Congress legislation which
would improve the federal system of criminal justice.”72 In its working papers, the Commission

63 See Gardner, supra note 20, at 683. The house pigeon example discussed in the Gardner article stems from a 19th
century English law addressed in the common-law case of Cotterill v. Penn. Id. at 679.
64 E.g., MODEL PENAL CODE § 2.04 (1985) (recognizing that ignorance or mistake is a defense if it negates the mental
state required for a material element of the offense, with exceptions).
65 See infra § “Selected Additional Mens Rea Issues in Federal Law.”
66 E.g., Robinson & Grall, supra note 53, at 706-07 (“A major defect of the Model Penal Code is its failure to define
adequately the three kinds of objective elements of an offense,” which is “essential for proper application of the defined
culpability terms.”); Kenneth W. Simons, Should the Model Penal Code’s Mens Rea Provisions Be Amended?, 1 OHIO
ST. J. CRIM. L. 179, 182-84 (2003) (diagnosing various problems).
67 Kenneth W. Simons, Rethinking Mental States, 72 B.U. L. REV. 463, 474 (1992).
68 Robinson & Grall, supra note 53, at 715.
69 Simons, Model Penal Code’s Mens Rea Provisions, supra note 66, at 180.
70 See Shen & Hoffman, supra note 33, at 1318 (“Whether in actual legislation, common law, or simply norms accepted
by lawyers and judges, the MPC has become ‘a standard part of the furniture of the criminal law.’” (citation omitted));
Batey, supra note 7, at 341 (indicating that as of 2001, “a substantial minority” of U.S. jurisdictions used the culpability
structure reflected in Section 2.02 of the MPC).
71 United States v. U.S. Gypsum Co., 438 U.S. 422, 444 (1978).
72 Pub. L. No. 89-801. 80 Stat. 1516 (1966).
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painted a rather unflattering picture of the state of mens rea requirements for federal crimes.73 The
Commission noted that in contrast with the MPC, federal statutory law did not contain uniform
and defined mental-state standards or rules of construction for the application of mens rea
terms.74 Instead, according to the Commission, federal criminal statutes drew from common-law
terminology in articulating mental-state requirements (if at all) on an ad hoc, statute-by-statute
basis.75 The Commission identified, in Title 18 of the U.S. Code alone, 78 different mens rea
terms.76 According to the Commission, this “staggering array” of mental-state terms did not
“reflect accurately or consistently what are the mental elements of the various crimes,” nor was
there any “discernible pattern or consistent rationale” for why particular terms were used in
particular statutes.77 As such, the Commission acknowledged that courts were left to discern what
Congress meant by including (or not including) one of the plethora of terms in any given context,
which led to the same terms having different, and sometimes inconsistent, meanings depending
on the statute.78
The Commission’s final report and recommendations, submitted to Congress and the President in
1971, proposed, among other things, to remedy the confusion over federal mens rea requirements
by establishing generally applicable culpability rules and definitions similar to those found in the
MPC.79 Legislation introduced based on the Commission’s report gained some traction but did
not become law.80 More recent legislation aimed at altering federal mens rea standards has also
been introduced but has not become law;81 as such, it remains that the U.S. Code has no general
mens rea term definitions or interpretive rules, and dozens of different terms are used throughout
the Code.82 Courts construe these terms “depending on the circumstances of the case and a
reading of congressional intent,” with the result that identical mens rea terms “vary significantly”
from statute to statute.83 In other words, ascertaining the mens rea required for a federal crime
will often necessitate reference to judicial decisions construing the language used to define that
particular offense.
For the foregoing reasons, and given that at least one estimate puts the number of federal statutes
carrying criminal penalties in the thousands,84 it would be unwieldy to examine comprehensively
federal mens rea requirements in a systematic way. Instead, this section of the report (1) examines
more broadly the interpretive approaches and presumptions that the Supreme Court and other
federal courts have utilized to glean congressional intent in construing the mental-state
requirements (if any) of federal criminal statutes; (2) provides a survey of mental-state
requirements under federal law, loosely grouped along the lines of the MPC’s culpability

73 See 1 NAT’L COMM’N ON REFORM OF FED. CRIM. L., WORKING PAPERS 118-20 (1970).
74 Id. at 119.
75 Id.
76 Id. at 119-20.
77 Id.
78 Id. at 120-21.
79 See NAT’L COMM’N ON REFORM OF FED. CRIM. L., FINAL REPORT: PROPOSED NEW FEDERAL CRIMINAL CODE 27-29
(1971), https://www.ndcourts.gov/Media/Default/Legal%20Resources/legal-research/criminal-code/FinalReport.pdf.
80 E.g., Criminal Code Reform Act of 1977, S. 1437, 95th Cong. ch. 3 (as passed by Senate, Jan. 30, 1978).
81 E.g., Mens Rea Reform Act of 2018, S. 3118, 115th Cong. (2018).
82 Moohr, supra note 13, at 692.
83 Id. at 693.
84 John G. Malcolm, Morally Innocent, Legally Guilty: The Case for Mens Rea Reform, 18 FEDERALIST SOC’Y REV. 40,
41 (2017). This number does not include federal regulations that implicate criminal penalties, which may number in the
thousands as well. Id.
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categorizations; and (3) addresses certain additional aspects of federal criminal liability that
implicate mens rea—specifically, inchoate offenses of attempt and conspiracy, corporate criminal
liability, and defenses.
Federal Mens Rea Interpretive Approach
The Supreme Court has “long recognized that determining the mental state required for
commission of a federal crime requires construction of the statute and inference of the intent of
Congress.”85 Three questions routinely arise with respect to determining the requisite mental state
for a particular federal crime: (1) whether the statute establishing the crime contains a mental-
state requirement or requirements; (2) if the statute contains mental-state requirements, which
elements of the offense must meet which requirements; and (3) what the mental-state
requirements mean.86 Because statutory language is not always clear, the federal courts have
“developed a rich—if somewhat untidy—body of substantive background principles” and
presumptions that guide the interpretive exercise.87 This section and the next address each of the
three questions identified above and the relevant principles and presumptions that courts may
apply to help answer those questions.
Whether Mens Rea is Required
Because the language of a statute is the starting point in statutory construction,88 a federal
criminal statute containing a mens rea term such as “knowingly” clearly indicates that Congress
meant to require some culpable mental state.89 When Congress omits an express mens rea
requirement from the statutory text, however, the question arises as to whether that omission was
intentional—in other words, whether Congress intended to dispense with any mental-state
requirement and make the offense one of strict liability.90 In a series of cases, the Supreme Court
has recognized, at least with respect to federal offenses based on traditional common-law crimes,
a “presumption in favor of scienter,”91 meaning the Court will ordinarily presume a “degree of
knowledge sufficient to make a person legally responsible for the consequences of his or her act
or omission.”92 Put differently, the Court has held that ordinarily “some indication of
congressional intent, express or implied, is required to dispense with mens rea as an element of a

85 Staples v. United States, 511 U.S. 600, 605 (1994) (citation, internal alteration, and internal quotation marks
omitted).
86 E.g., id. at 605-08 (addressing existence of knowledge requirement in statute with no explicit mens rea and
application of that requirement to different elements of offense).
87 Eric A. Johnson, Rethinking the Presumption of Mens Rea, 47 WAKE FOREST L. REV. 769, 770 (2012); see United
States v. Figueroa, 165 F.3d 111, 119 (2d Cir. 1998) (Sotomayor, J.) (referencing “principles of construction
underlying the criminal law” as “signposts to congressional intent”).
88 Staples, 511 U.S. at 605.
89 See Figueroa, 165 F.3d at 114 (“By using the word ‘knowingly,’ Congress chose to include some knowledge
requirement for a conviction under [the statute].”).
90 “Strict-liability crime” is defined as one “for which the action alone is enough to warrant a conviction, with no need
to prove a mental state; specif., a crime that does not require a mens rea element, such as traffic offenses and illegal
sales of intoxicating liquor.” Strict-Liability Crime, BLACK’S LAW DICTIONARY (11th ed. 2019). Strict liability may
apply to only one or some of the elements of an offense. E.g., Staples, 511 U.S. at 609 (addressing statute imposing
strict liability as to unregistered nature of firearm but requiring knowledge of features of firearm making it subject to
regulation).
91 Rehaif v. United States, 139 S. Ct. 2191, 2195 (2019).
92 Id. (citation, internal alteration, and internal quotation marks omitted).
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crime,”93 and mere omission of a mens rea term will not be considered a sufficient indication of
such intent.94
The genesis of the presumption in favor of scienter can be traced to the Supreme Court’s 1952
decision in Morissette v. United States.95 In Morissette, the Court, in reading an intent
requirement into a statute proscribing theft or conversion of federal property,96 spoke broadly of
intent as “so inherent in the idea of” crimes codified from common law “that it required no
statutory affirmation” and counseled “caution in assuming that Congress, without clear
expression,” sought to eliminate any mental-state requirement.97 A later Supreme Court decision
more clearly articulated a presumption that Congress “legislated against the background of . . .
traditional legal concepts which render intent a critical factor”98 and further acknowledged such a
presumption as consistent with a separate interpretive doctrine that “ambiguity concerning the
ambit of criminal statutes should be resolved in favor of lenity.”99
Assuming the presumption of mens rea applies, and thus that a mental-state requirement should
be read into a statute that does not explicitly contain one, the question becomes what kind of
mental state is required. In this respect, the Supreme Court has held that “[t]he presumption in
favor of scienter requires a court to read into a statute only that mens rea which is necessary to
separate wrongful conduct from ‘otherwise innocent conduct.’”100 Typically, the standard of
knowledge is sufficient to meet this requirement.101 For instance, in Staples v. United States, the
Court held that a statute making it unlawful to receive or possess certain kinds of unregistered
firearms102 required knowledge of the features of the firearm that brought it within the scope of

93 Staples, 511 U.S. at 606.
94 Morissette v. United States, 342 U.S. 246, 263 (1952).
95 Id.
96 18 U.S.C. § 641.
97 Morissette, 342 U.S. at 252, 254 n.14. The Morissette Court rooted its decision in the principle that “where Congress
borrows terms of art in which are accumulated the legal tradition and meaning of centuries of practice, it presumably
knows and adopts the cluster of ideas that were attached to each borrowed word in the body of learning from which it
was taken and the meaning its use will convey to the judicial mind unless otherwise instructed.” Id. at 263. In
accordance with this principle, the Court recognized that “[s]tealing, larceny, and its variants and equivalents” were
well-known at common law, and judicial precedent “consistently retained the requirement of intent in larceny-type
offenses.” Id. at 261. The Court in later decisions has appeared to recognize the applicability of the presumption even to
statutes lacking direct common-law antecedents, however. E.g., Rehaif v. United States, 139 S. Ct. 2191, 2195 (2019)
(acknowledging that presumption is “traceable to the common law” but referring to the presumption as applicable
generally to “criminal statutes”).
98 United States v. U.S. Gypsum Co., 438 U.S. 422, 437 (1978).
99 Id. (quoting Rewis v. United States, 401 U.S. 808, 812 (1971)).
100 Carter v. United States, 530 U.S. 255, 269 (2000) (quoting United States v. X-Citement Video, Inc., 513 U.S. 64, 72
(1994)). As explained in more detail infra, this formulation also speaks to the question of which elements of a statutory
offense bear a mens rea requirement.
101 See Carter, 530 U.S. at 268 (concluding that presumption in favor of scienter required proof “of general intent—
that is, that the defendant possessed knowledge with respect to the actus reus of the crime,” but caveating that “some
situations may call for implying a specific intent requirement into statutory text”); Elonis v. United States, 135 S. Ct.
2001, 2012 (2015) (concluding that statute proscribing transmission of threatening communication required purpose to
threaten or knowledge of threatening nature of communication, but declining to address whether recklessness as to
threat would be sufficient); John Shepard Wiley Jr., Not Guilty by Reason of Blamelessness: Culpability in Federal
Criminal Interpretation, 85 VA. L. REV. 1021, 1112 (1999) (“[W]hen Congress has omitted all culpability language, . . .
[t]he Court apparently has adopted the ‘knowledge’ standard as the default[.]”).
102 26 U.S.C. § 5861(d).
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the statute.103 In reaching its conclusion, the Court noted that omitting a requirement that a
“defendant know the facts that make his conduct illegal” would “impose criminal sanctions on a
class of persons whose mental state . . . makes their actions entirely innocent.”104
The Court also has recognized a class of “‘public welfare’ or ‘regulatory’ offenses” to which the
presumption will not apply (i.e., offenses where statutory silence is treated as imposing “a form of
strict criminal liability” by “not requir[ing] the defendant to know the facts that make his conduct
illegal.”)105 Typically, “such offenses involve statutes that regulate potentially harmful or
injurious items” or activities, which put individuals on notice of the likelihood of regulation, 106
and impose relatively small penalties.107 One of the earliest examples of the Supreme Court’s
recognition of a public welfare offense lacking a mens rea requirement is United States v. Balint,
in which the Court addressed a statute prohibiting the sale of certain narcotics without a tax form
issued by the federal government.108 The defendants argued that the government was required to
prove that they knew the drugs they sold —derivatives of opium and coca leaves—were covered
by the statute, but the Court concluded that the statute did not require proof of such knowledge.109
In so doing, the Court recognized a class of “regulatory measures” lacking a scienter requirement
where the emphasis was “upon achievement of some social betterment rather than . . .
punishment.”110 Acknowledging the question as one of congressional intent, the Court determined
that the statute at issue fell into this class given its “manifest purpose . . . to require every person
dealing in drugs to ascertain at his peril whether that which he sells comes within the inhibition of
the statute,” noting that the opportunity of the seller to determine the nature of the drug being sold
and the difficulty of proving knowledge “[d]oubtless . . . contributed to [Congress’s] conclusion”
that such knowledge should not be required.111
Subsequent cases have appeared to back away from the somewhat broad conception of strict-
liability crimes presented in Balint, emphasizing the “limited circumstances” in which they will
be recognized.112 Ultimately, several factors may be relevant to a court’s determination of
whether a particular criminal statute imposes strict liability, including the nature of the statute and
the particular activity or item regulated, the purpose of the criminal prohibition (i.e., punishment
of wrongdoing versus protection of the public), the degree to which a defendant will be in a
position to ascertain the relevant facts, and the severity of the penalties.113

103 511 U.S. 600, 619 (1994).
104 Id. at 605, 614-15.
105 Id. at 606-07.
106 Id. at 607.
107 Morissette v. United States, 342 U.S. 246, 254, 256 (1952) (recognizing criminal regulatory offenses “which
heighten the duties of those in control of particular industries, trades, properties or activities that affect public health,
safety or welfare” and noting that “penalties [for such offenses] commonly are relatively small, and conviction does no
grave damage to an offender’s reputation”).
108 258 U.S. 250, 251 (1922).
109 Id. at 251, 253-54.
110 Id. at 252.
111 Id. at 254.
112 Staples v. United States, 511 U.S. 600, 607 (1994); see also United States v. U.S. Gypsum Co., 438 U.S. 422, 437-
38 (1978) (“[T]he limited circumstances in which Congress has created and this Court has recognized such offenses . . .
attest to their generally disfavored status.”); Morissette, 342 U.S. at 251 (referencing “universal and persistent” notion
that crime requires intention).
113 See, e.g., Staples, 511 U.S. at 607; Morissette, 342 U.S. at 255-56; United States v. Dotterweich, 320 U.S. 277, 281-
82 (1943); Balint, 258 U.S. at 254.
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In short, though the line between a public welfare offense and a traditional offense to which the
presumption of mens rea applies “can be difficult to draw,”114 a court will generally look to “the
nature of the statute and the particular character of the items regulated to determine whether
congressional silence concerning the mental element of the offense should be interpreted as
dispensing with conventional mens rea requirements.”115 Strictly speaking, however, even so-
called “strict liability” public welfare offenses are not viewed as completely dispensing with any
state-of-mind requirement—rather, they require “only so much knowledge as is necessary to
provide defendants with reasonable notification that their actions are subject to strict
regulation.”116 Put differently, public welfare offenses “require at least that the defendant know
that he is dealing with some dangerous or deleterious substance” but not necessarily “the facts
that make his conduct fit the definition of the offense.”117
The absence of a mens rea requirement in a criminal statute may present constitutional difficulties
in particular contexts. For instance, the Supreme Court in United States v. X-Citement Video, Inc.
interpreted a statute criminalizing distribution of sexually explicit visual depictions of minors118
as requiring a defendant to have knowledge of the minority of those involved, in part based on
First Amendment concerns.119 Ordinarily, restrictions on speech based on its content are
presumptively unconstitutional,120 and although child pornography generally falls within an
exception for unprotected speech,121 the X-Citement Video Court recognized prior precedent as
suggesting that the absence of a mens rea requirement as to the character of such materials could
“raise serious constitutional doubts” under the First Amendment.122 Additionally, some lower
courts have suggested that “the imposition of severe penalties, especially a felony conviction,” for
a strict-liability crime may violate the Due Process Clause of the Fifth Amendment,123 as “a
person acting with a completely innocent state of mind could be subjected to a severe penalty and
grave damage to his reputation.”124 Nevertheless, although the Supreme Court has struck down
one strict-liability city ordinance on due-process grounds in a fairly unique circumstance

114 Leonid Traps, “Knowingly” Ignorant: Mens Rea Distribution in Federal Criminal Law After Flores-Figueroa, 112
COLUM. L. REV. 628, 633 (2012).
115 Staples, 511 U.S. at 607.
116 United States v. Figueroa, 165 F.3d 111, 116 (2d Cir. 1998) (Sotomayor, J.).
117 Staples, 511 U.S. at 607 n.3.
118 18 U.S.C. § 2252(a).
119 513 U.S. 64, 78 (1994).
120 CRS In Focus IF11072, The First Amendment: Categories of Speech, by Victoria L. Killion.
121 Id.
122 513 U.S. at 78; see United States v. Class, 930 F.3d 460, 468-70 (D.C. Cir. 2019) (noting that due-process
vagueness analysis is “more searching” where law imposes criminal penalties, threatens to inhibit exercise of a
constitutional right, and lacks a scienter requirement, but upholding statute prohibiting firearm possession on Capitol
grounds despite lack of requirement that defendant know he is on Capitol grounds); but cf. United States v. Wilson, 565
F.3d 1059, 1068 (8th Cir. 2009) (noting that “the First Amendment calculus is different depending on the proximity of
the defendant to the victim” and concluding that criminal prohibition on production of child pornography is “not
entitled to any mens rea safeguards”).
123 United States v. Enochs, 857 F.2d 491, 494 n.2 (8th Cir. 1988); see also United States v. Wulff, 758 F.2d 1121,
1125 (6th Cir. 1985) (indicating that mens rea may only constitutionally be eliminated “where (1) the penalty is
relatively small, and (2) where conviction does not gravely besmirch,” and concluding that felony provision of
Migratory Bird Treaty Act “d[id] not meet these criteria”); cf. United States v. DeCoster, 828 F.3d 626, 633 (8th Cir.
2016) (“The elimination of a mens rea requirement does not violate the Due Process Clause for a public welfare
offense where the penalty is ‘relatively small,’ the conviction does not gravely damage the defendant's reputation, and
congressional intent supports the imposition of the penalty.”).
124 Wulff, 758 F.2d at 1125.
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involving “wholly passive” conduct with no notice or opportunity to comply,125 it has at other
times appeared to affirm the constitutionality of strict-liability crimes more generally.126 Further,
at least one federal appellate court has rejected the proposition that strict-liability felonies are per
se unconstitutional.127 As such, the precise constitutional limits of strict-liability public welfare
offenses are unclear.128
Application of Mens Rea to Specific Elements
Assuming either that Congress has provided a mens rea requirement in a federal criminal statute,
or that a court concludes a statute silent on the issue carries one, the question may arise as to
which elements of the crime must meet that requirement. One innovation of the Model Penal
Code was its recognition that the mental state for a particular crime should be analyzed on an
element-by-element basis.129 This approach is also generally employed under federal law.130 In
some statutes, Congress may have provided relatively clear instruction as to what mens rea term
must be established for distinct components of the crime at issue—for example, 18 U.S.C. § 1591
makes it a crime to “knowingly” recruit a person “knowing” or “in reckless disregard of the fact”
that force or other proscribed means will be used to cause the person to engage in a commercial
sex act, or that the person is under the age of 18 and will be caused to engage in a commercial sex
act.131 It is often the case, however, that Congress will provide penalties for a “willful” or
“knowing” violation of a statute that contains multiple elements, for instance, or will omit a
textual mental-state requirement for a crime that is presumed to have at least one as described
above.132 In this circumstance, courts are left to glean congressional intent as to which elements
must meet the mens rea term that either is specified or presumed.

125 Lambert v. California, 355 U.S. 225, 228-29 (1957). The provision in Lambert made it unlawful for any person
convicted of a felony “to be or remain in Los Angeles for a period of more than five days without registering” with the
Chief of Police. Id. at 226. In striking down the ordinance, the Court reasoned that notice is “[e]ngrained in [the]
concept of due process.” Id. at 228.
126 See Balint, 258 U.S. at 252 (“It has been objected that punishment of a person for an act in violation of law when
ignorant of the facts making it so, is an absence of due process of law. But that objection is considered and overruled . .
. .”); U.S. Gypsum Company, 438 U.S. at 437 (stating that “strict-liability offenses are not unknown to the criminal law
and do not invariably offend constitutional requirements”). The Court has also noted the muted impact of Lambert,
stating that its “application has been limited” and signaling some agreement with the proposition that it “stands as an
isolated deviation from the strong current of precedents[.]” Texaco, Inc. v. Short, 454 U.S. 516, 537 (1982) (citation
and internal quotation marks omitted).
127 United States v. Engler, 806 F.2d 425, 433 (3d Cir. 1986) (stating that bright-line rule regarding felonies “ignore[s]
a formidable line of cases imposing strict liability in felony cases without proof of scienter”); see also United States v.
Stepanets, __F.3d__, No. 19-1471, 2021 WL 748385, at *6 (1st Cir. Feb. 26, 2021) (“[Precedent] refutes the notion that
due process requires there to be a mens rea element in an offense as a categorical matter.”).
128 Engler, 806 F.2d at 434 (“The Supreme Court has indicated that the due process clause may set some limits on the
imposition of strict criminal liability, but it has not set forth definite guidelines as to what those limits might be.”)
129 See supra § “Model Penal Code Approach.”
130 See, e.g., Rehaif v. United States, 139 S. Ct. 2191, 2195-96 (2019) (assessing which elements of statutory crime
require knowledge).
131 18 U.S.C. § 1591(a). The statute also limits the “reckless disregard” standard for certain conduct and provides an
exception to the requirement of knowledge or reckless disregard of age where “the defendant had a reasonable
opportunity to observe the person” recruited. Id. §§ 1591(a), (c).
132 E.g., Rehaif, 139 S. Ct. at 2196 (referring to circumstance where mens rea term “introduces a long statutory phrase,
such that questions may reasonably arise about how far into the statute the modifier extends”); see supra notes 90-99
and accompanying text (discussing judicial development of presumption in favor of scienter).
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As with the question of whether a statute has a mens rea requirement at all, federal courts have
applied certain presumptions and general principles that guide them in determining which
elements of a crime must meet a mental-state requirement. First, the Supreme Court has made
clear that the presumption in favor of scienter applies to “each of the statutory elements that
criminalize otherwise innocent conduct.”133 Put another way: “Absent clear congressional intent
to the contrary, statutes defining federal crimes are . . . normally read to contain a mens rea
requirement that attaches to enough elements of the crime that together would be sufficient to
constitute an act in violation of the law.”134 For instance, in United States v. Bruguier, a federal
appellate court concluded that a federal statute proscribing “knowingly” engaging in a sexual act
with another person “if that other person is . . . incapable of appraising the nature of the conduct”
or physically incapable of expressing lack of consent135 required both knowingly engaging in the
sexual act and knowledge that the other person could not appraise the nature of the conduct or
express lack of consent.136 In reaching this conclusion, the court noted that knowingly engaging
in a sexual act with another person “is not inherently criminal under federal law, barring some
other attendant circumstance.”137 By contrast, in United States v. Feola, the Supreme Court
determined that a statute criminalizing assault on a federal officer “while engaged in or on
account of the performance” of official duties138 did not require the assailant to be aware that the
victim was a federal officer, emphasizing that a perpetrator “knows from the very outset that his
planned course of conduct is wrongful” and thus the “situation is not one where legitimate
conduct becomes unlawful solely because of the identity of the individual or agency affected.”139
The distributive approach emphasizing a distinction between elements that make conduct
criminal (as in Bruguier, where incapacity and knowledge thereof made conduct criminal that
otherwise was not inherently so) and elements that “merely aggravate[] conduct that already is
criminal” (as in Feola, where the element at issue merely defined a subset of assaults as federally
punishable) has been subject to criticism for its lack of clarity.140 Recent Supreme Court cases
have at times appeared to skirt the lack of clarity and move towards a rule more akin to the MPC
approach—i.e., that, absent an indication of congressional intent to the contrary, a mental-state
requirement applies to each material element of the offense.141 For example, in Flores-Figueroa v.
United States, the Court addressed a provision imposing a mandatory two-year prison term on
certain persons who “knowingly transfer[], possess[], or use[], without lawful authority, a means
of identification of another person.”142 In a largely textual analysis, the Court concluded that the
statute required proof that the defendant knew that the “means of identification” belonged to
another person, based in part on the recognition that “courts ordinarily read a phrase in a criminal
statute that introduces the elements of a crime with the word ‘knowingly’ as applying that word to

133 United States v. X-Citement Video, Inc., 513 U.S. 64, 72 (1994).
134 United States v. Figueroa, 165 F.3d 111, 116 (2d Cir. 1998) (Sotomayor, J.).
135 18 U.S.C. § 2242. The statute is jurisdictionally limited to the special maritime and territorial jurisdiction of the
United States and certain federal facilities. Id.
136 735 F.3d 754, 763 (8th Cir. 2013).
137 Id. at 761.
138 420 U.S. 671, 673 n.1 (1975) (quoting 18 U.S.C. § 111).
139 Id. at 685.
140 See Johnson, Rethinking the Presumption of Mens Rea, supra note 87, at 780 (“The academic commentary has been
broadly critical of this limitation on the mens rea presumption.”).
141 See supra note 62 and accompanying text.
142 556 U.S. 646, 647 (2009) (quoting 18 U.S.C. § 1028A(a)(1)).
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each element.”143 Some observers subsequently noted that this language could be viewed as
“parallel[ing] the distributive default of the Model Penal Code,”144 though several Justices wrote
separately in the case to make clear that they did not necessarily agree with the language as a
“normative description of what courts should ordinarily do when interpreting such statutes.”145
The federal courts of appeals have largely recognized that Flores-Figueroa’s language does not
“establish a bright-line rule that a specified mens rea always applies to every element of the
offense.”146 In contrast, in Torres v. Lynch, the Court explained that “[i]n general, courts interpret
criminal statutes to require that a defendant possess a mens rea, or guilty mind, as to every
element of an offense.”147 Moreover, in Rehaif v. United States, the Court indicated that the
presumption of scienter as to an element “applies with equal or greater force when Congress
includes a general scienter provision in the statute itself,” citing the MPC provision that
establishes a default distributive rule applying to all material elements.148 The Court in Rehaif
also gestured to the “innocent conduct” analysis, however, in concluding that the statute at
issue—which penalized “knowing[]” violations of a provision proscribing firearm possession by
aliens unlawfully in the United States—required application of the knowledge standard to both
the defendant’s conduct and immigration status, specifying that “the possession of a gun can be
entirely innocent” and thus applying mens rea to immigration status helped “separate wrongful
from innocent acts.”149
Regardless of whether or when a presumption of scienter attaches to other elements of a criminal
offense, what is clear is that no presumption applies with respect to jurisdictional elements—i.e.,
elements that “simply ensure that the Federal Government has the constitutional authority to
regulate the defendant’s conduct” by, for instance, limiting an offense to conduct “in or affecting
commerce.”150 As the Court in Rehaif stated: “Because jurisdictional elements normally have

143 Id. at 652.
144 Traps, supra note 114, at 629; see also Darryl K. Brown, Federal Mens Rea Interpretation and the Limits of
Culpability’s Relevance, 75 L. & CONTEMP. PROBS. 109, 121 (2012) (“If [the Court’s] claim is taken as a canon of
construction, it should work much like the MPC’s provision that dictates a culpability term should apply to all material
elements.”).
145 Flores-Figueroa, 556 U.S. at 658 (Scalia, J., concurring); see also id. at 660 (Alito, J., concurring) (viewing as
“fair” a “general presumption” that a specified mens rea applies “to all the elements of the offense” but collecting
contextual instances where that presumption is rebutted).
146 United States v. Washington, 743 F.3d 938, 942 (4th Cir. 2014); see also United States v. Price, 921 F.3d 777, 786
(9th Cir. 2019) (“We have explicitly rejected the notion that the Court’s reading of ‘knowingly’ in Flores-Figueroa
compels the same reading in every criminal statute that uses the word ‘knowingly.’”); United States v. Cox, 577 F.3d
833, 838 (7th Cir. 2009) (indicating that Flores-Figueroa “did not establish a rule for all circumstances”); United States
v. Daniels, 653 F.3d 399, 410 (6th Cir. 2011) (“Flores-Figueroa does not compel a particular interpretation . . . .
Rather, the resolution of this issue depends on the relative weight given to text and context.”). Some courts have
expressly treated Flores-Figueroa as recognizing a presumption that a stated mens rea term, or at least a “knowingly”
term at the beginning of a sequence of statutory elements, applies to every subsequent element, which can be rebutted
“where the context or background circumstances of a statute lead to a different reading.” United States v. Bruguier, 735
F.3d 754, 761 (8th Cir. 2013) (citation and internal quotation marks omitted); United States v. Daniels, 685 F.3d 1237,
1248-49 (11th Cir. 2012) (“Although there is a general presumption that a knowing mens rea applies to every element
in a statute, cases concerned with the protection of minors are within a special context, where that presumption is
rebutted.”).
147 136 S. Ct. 1619, 1630 (2016).
148 139 S. Ct. 2191, 2195 (2019) (citing MODEL PENAL CODE § 2.02(4) (1985)).
149 Id. at 2197.
150 Id. at 2196 (noting that “jurisdictional elements do not describe the ‘evil Congress seeks to prevent’” (quoting
Torres, 136 S. Ct. at 1630)).
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nothing to do with the wrongfulness of the defendant’s conduct, such elements are not subject to
the presumption in favor of scienter.”151
Meaning of Mens Rea Standards in Federal Statutes
Beyond the questions of whether a statute contains mens rea requirements and, if so, which
elements carry those requirements is the question of what the mens rea standards established
under federal law actually mean. Many of the dozens of different mens rea terms in federal law
are undefined.152 Further, the terms used may be conclusory and give little indication of what
mental state is called for—for instance, terms such as “corruptly,” “maliciously,” “unlawfully,”
and “feloniously” can all be found in Title 18 alone.153 As such, understanding what mental state
is required for a given federal crime will almost necessarily require reference to judicial opinions
construing that particular provision. Even then, “the same terms are defined differently depending
on which substantive crime is at issue, which federal circuit one is in, and which judge within a
given district is crafting the jury’s instructions.”154
As the National Commission on Reform of Federal Criminal Laws acknowledged decades ago,
however, judicial opinions interpreting federal mens rea terms “display far fewer mental states
than the statutory language” might suggest.155 Of “paramount importance” in federal criminal law
are the concepts of “intention” or, in the language of the MPC, “purpose,” “as well as knowledge
or awareness.”156 Less common, though still relevant, are concepts embodied at least partially in
the MPC’s frameworks for recklessness and negligence.157 Different courts may have different
approaches to these concepts and the definitions they entail. This section provides an overview of

151 Id. Additionally, relying on the notion that only the mens rea necessary to separate wrongful from otherwise
innocent conduct is required, courts have found no need to read a mens rea requirement into provisions that merely
enhance the sentence for conduct that is already criminally proscribed. E.g., Dean v. United States, 556 U.S. 568, 575-
76 (2009) (noting that “it is not unusual to punish individuals for the unintended consequences of their unlawful acts”
and concluding no mens rea applied to a “sentencing enhancement . . . account[ing] for the risk of harm resulting from
the manner in which the crime is carried out”); United States v. McDuffy, 890 F.3d 796, 801 (9th Cir. 2018) (“Thus,
the presumption in favor of scienter is lessened, if not altogether absent, when considering sentencing enhancement
provisions.”). Questions may arise as to when a provision in a statute constitutes an element of the offense versus an
enhancement provision. Cf. United States v. Burwell, 690 F.3d 500, 505, 508 (D.C. Cir. 2012) (calling “misguided” the
suggestion “that the label ‘element of the offense,’ as opposed to ‘sentencing factor,’ is determinative of the mens rea
requirement” and emphasizing that “certain offense elements do not require proof of an additional mens rea so long as
the offense as a whole carries a scienter requirement that separates innocent from criminal conduct”).
152 See supra notes 72-78; James A. Macleod, Belief States in Criminal Law, 68 OKLA. L. REV. 497, 511 (2016) (“The
federal criminal code employs a far greater array of mental state terms than does the MPC, and these terms are typically
left undefined in the statutes in which they are found.”).
153 See 1 WORKING PAPERS, supra note 73, at 119 (citing 18 U.S.C. §§ 201, 549, 1427, & 1506).
154 Macleod, supra note 152, at 511. Because mens rea, as “an ingredient of the crime charged,” is “a question of fact
which must be submitted to the jury,” Morissette v. United States, 342 U.S. 246, 274 (1952), judicial interpretations of
statutory mens rea requirements typically arise in the context of challenges to the trial court’s jury instructions defining
the mental-state element that must be proved. See, e.g., Liparota v. United States, 471 U.S. 419, 423 (1985) (involving
challenge to jury instructions based on district court’s refusal to instruct jury that specific intent was required).
155 Id. at 120.
156 O’MALLEY, GRENIG, & LEE, supra note 6, § 17:01.
157 MODEL CRIM. JURY INSTRUCTIONS ch. 5 (U.S. CT. APPEALS, 3D CIR. 2018) [hereinafter THIRD CIRCUIT JURY
INSTRUCTIONS], https://www.ca3.uscourts.gov/model-criminal-jury-table-contents-and-instructions (“Federal crimes
commonly include the mental states intentionally, knowingly, or willfully, and less commonly recklessly or
negligently.”).
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the meanings of some of the most common mens rea standards under federal law, grouped loosely
into categories similar to those recognized in the MPC.
Intentionally, Knowingly, and Willfully
The terms “intentionally,” “knowingly,” and “willfully” are among those “used most frequently”
in federal criminal statutes, but as with other federal mens rea terms, they have “eluded precise
definition.”158 It seems that all three terms require at least some degree of conscious, subjective
awareness of the element to which the requirement attaches.159 Beyond this baseline, the
meanings of the terms may vary or overlap considerably depending on the court, statute, and
context of their use.160
Intentionally and Knowingly
The concept of committing an offense “intentionally” has long been mired in confusion given the
varying usages of the term at common law and the rather unclear distinction between “specific
intent” and “general intent” crimes.161 In one view, intent might be thought to embody a
“bifurcated concept” embracing a requirement that a person “consciously desire[]” some result or
that they be aware that it “is practically certain,” whatever their desire.162 Under this approach,
any “limited distinction” between knowledge and intention or purpose is not “considered
important since ‘there is good reason for imposing liability whether the defendant desired or
merely knew of the practical certainty of the results.’”163 An ostensible blurring of the concepts of
intention and knowledge is embodied in some federal court jury instructions that define
“knowingly” as “voluntarily and intentionally,”164 as well as cases that may treat the term “intent”
as “requir[ing] only that the defendant reasonably knew the proscribed result would occur” or as

158 O’MALLEY, GRENIG, & LEE, supra note 6, § 17:01. A fourth term bearing similarity to the other three is
“maliciously,” which, in one formulation, denotes intent to do a prohibited act without justification, mitigation, or
excuse. E.g., United States v. Kelly, 676 F.3d 912, 918 (9th Cir. 2012); cf. United States v. Grady, 746 F.3d 846, 849
(7th Cir. 2014) (approving jury instruction defining “maliciously” as “intentionally or with deliberate disregard of the
likelihood that damage or injury would result” but omitting proposed addition of phrase “without just cause or reason”).
The concept of “malice” is used to define the requisite mental states for certain federal homicide crimes, which also
provide an example of one circumstance where the “mitigation or excuse” component of the above definition is
relevant—murder and voluntary manslaughter both require intent to kill or cause serious bodily injury (or at least
extreme recklessness as to such result), but voluntary manslaughter bears a mitigating element of “sudden quarrel or
heat of passion” that renders it “without malice.” United States v. Serawop, 410 F.3d 656, 664 (10th Cir. 2005); see
United States v. Delaney, 717 F.3d 553, 557 (7th Cir. 2013) (“This is puzzling, because ‘malice aforethought’ in the
statute means intent and so what does it mean to say that a person did something intentionally but without malice?”).
Malice can also bear a distinct meaning that incorporates notions of “evil purpose or motive” in at least one statute. See
United States v. Hassouneh, 199 F.3d 175, 181 (4th Cir. 2000) (“[T]he history surrounding the progression of the
Bomb Hoax Act confirms that Congress intended the term ‘acts willfully and maliciously’ to mean ‘acts with an evil
purpose or motive.’”).
159 Or at least a high enough degree of risk that the existence of the element is “virtually certain.” Shen & Hoffman,
supra note 33, at 1312 (describing “most recent major fault line in the law of intentionality” as distinguishing between
“desire-based intent” and “a new category of ‘recklessness-plus’” that is “grounded in the degree of risk the actor is
consciously undertaking”).
160 E.g., Bryan v. United States, 524 U.S. 184, 191 (1998) (“The word ‘willfully’ is sometimes said to be ‘a word of
many meanings’ whose construction is often dependent on the context in which it appears.”).
161 See supra § “Background.”
162 United States v. U.S. Gypsum Co., 438 U.S. 422, 445 (1978) (quoting WAYNE R. LAFAVE & AUSTIN W. SCOTT, JR.,
CRIMINAL LAW 196 (1972)).
163 Id.
164 E.g., United States v. Tracy, 36 F.3d 187, 194 (1st Cir. 1994).
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requiring that the defendant “specifically intended such an outcome as his purpose” depending on
the common-law categorizations of specific versus general intent.165 This approach may lead to
disagreement as to whether particular federal statutes with an intent requirement call for merely
awareness or a higher degree of purpose or desire,166 though courts have often applied a general
intent standard as a default.167
The approach168 largely reflected in the MPC and some federal precedent is to distinguish
between “intention” or purpose on the one hand as being limited to a conscious object or desire,
and “knowledge” on the other hand as capturing a requirement of awareness of a high probability
or to a practical certainty.169 The Supreme Court in Bailey referenced this distinction approvingly
and suggested that intention or purpose “corresponds loosely with the common-law concept of
specific intent, while ‘knowledge’ corresponds loosely with the concept of general intent.”170

165 United States v. Dyer, 589 F.3d 520, 528 (1st Cir. 2009); see also United States v. Tobin, 552 F.3d 29, 32-33 (1st
Cir. 2009) (“Although the word ‘intent’ can often mean with ‘knowledge’ that a particular result will follow, it
sometimes instead requires a ‘purpose’ to bring about a specific end.”). A specific intent requirement may even be
construed to encompass recklessness in some contexts. See United States v. McAnally, 666 F.2d 1116, 1119 (7th Cir.
1981) (“[T]raditionally in the criminal law an extreme form of recklessness has been treated as intentional . . . .”); but
see United States v. Adamson, 700 F.2d 953, 962 (5th Cir. 1983) (criticizing “loose references to recklessness” in
discussions of specific intent requirement of statute proscribing misapplication of bank funds). Recklessness as a mens
rea standard under federal law is discussed in more detail infra.
166 E.g., United States v. Veach, 455 F.3d 628, 632 (6th Cir. 2006) (acknowledging disagreement over whether statute
proscribing threatened assault of certain federal officials “with intent to . . . intimidate,” among other things, is specific
or general intent crime); United States v. Rodriguez, 416 F.3d 123, 126-27 (2d Cir. 2005) (disagreeing with Ninth
Circuit that immigration statute requires purpose to reenter U.S. illegally, rather than merely “knowingly and
intentionally” taking the action that constitutes an attempt to reenter). Depending on the statute, an intent requirement
may also be conditional, i.e., intent may be established if the defendant intends to take a proscribed action or produce a
proscribed result only “if necessary”; put differently, “a defendant may not negate a proscribed intent by requiring the
victim to comply with a condition the defendant has no right to impose.” Holloway v. United States, 526 U.S. 1, 11
(1999). This principle is consistent with the approach of the MPC. See MODEL PENAL CODE § 2.02(6) (1985) (“When a
particular purpose is an element of an offense, the element is established although such purpose is conditional, unless
the condition negatives the harm or evil sought to be prevented by the law defining the offense.”). Intent additionally
may be “transferred” where one has intent to harm a specific victim but a different victim is actually harmed instead.
See, e.g., United States v. Savage, 970 F.3d 217, 276 (3d Cir. 2020) (surveying application of doctrine under federal
law); cf. MODEL PENAL CODE § 2.03(2) (treating transferred intent as matter of causation).
167 E.g., United States v. Lynch, 881 F.3d 812, 815 (10th Cir. 2018) (“Where specific intent is not required, criminal
statutes are usually read to require ‘only that a defendant know the facts that make his conduct illegal.’” (citation
omitted)); United States v. Martinez, 49 F.3d 1398, 1401 (9th Cir. 1995), superseded by statute as recognized in United
States v. Randolph, 93 F.3d 656, 661 (9th Cir. 1996) (“[W]hen a statute does not contain any reference to intent,
general intent is ordinarily implied.”). As described supra, whether a particular federal statute establishes a general or
specific intent crime is ultimately a question of legislative intent that may depend on the text of the statute, how the
crime at issue was treated at common law, and legislative history, among other things. E.g., United States v. Lamott,
831 F.3d 1153, 1156-57 (9th Cir. 2016) (considering “[s]everal factors” as indicative of congressional intent to
establish general intent crime, including lack of use of phrase “with intent to,” common law precedent regarding assault
and battery, and legislative record surrounding passage of law).
168 O’MALLEY, GRENIG, & LEE, supra note 6, § 17:01 (quoting WAYNE R. LAFAVE, CRIMINAL LAW § 3.5 (4th ed.
2003)).
169 See supra § “Model Penal Code Approach.” Some federal courts may frame knowledge in terms of “belief” rather
than awareness, particularly in contexts such as sting operations where a circumstance element at issue may not
actually be present. E.g., United States v. Flores, 945 F.3d 687, 712 (2d Cir. 2019) (“[A]lthough knowledge is . . .
belief substantiated by veracity, in the context of a sting operation belief is tantamount to knowledge.” (citation and
internal quotation marks omitted)).
170 United States v. Bailey, 444 U.S. 394, 405 (1980); see also United States v. Ramamoorthy, 949 F.3d 955, 961 (6th
Cir. 2020) (“To commit a general-intent crime, a defendant must only intend to do the act that the law proscribes. To
commit a specific-intent crime, a defendant must do more than knowingly act in violation of the law. He must also act
with the purpose of violating the law.” (internal citations and quotation marks omitted)). One commentator has argued
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Some federal courts utilize a definition of “knowing” that approximates the MPC approach,
instructing that to act knowingly a defendant must have “realized what he was doing and [be]
aware of the nature of his conduct” rather than acting “through ignorance, mistake or accident.”171
Congress has also signaled an intent to distinguish between the two mens rea terms in this way in
particular statutes. For instance, prior to 1986, the Computer Fraud and Abuse Act (CFAA)
proscribed “knowingly” accessing a computer without authorization or exceeding authorized
access in certain circumstances.172 In its 1986 amendments, however, Congress changed the
standard from “knowingly” to “intentionally,” and the Senate report emphasized that the change
was meant to require “more than that one voluntarily engaged in conduct . . . . Such conduct . . .
must have been the person’s conscious objective.”173
For federal statutes that establish a “knowing” mens rea requirement, one issue that can arise
concerns a circumstance where a person may not have positive knowledge of the element at issue
“only because he consciously avoided it.”174 In this situation, every federal circuit has recognized
that so-called “willful blindness” or “deliberate ignorance” can equate to knowledge.175 Though
the precise formulations and requirements vary, courts “appear to agree on two basic
requirements: (1) The defendant must subjectively believe that there is a high probability that a
fact exists and (2) the defendant must take deliberate actions to avoid learning of that fact.”176 For
instance, if a person is found to be transporting narcotics in the trunk of their car and claims that
their suspicions were aroused by the smell of dryer sheets used to mask the narcotics’ odor but
that they did not actually know the trunk contained drugs, a willful blindness jury instruction may
be appropriate in a subsequent prosecution for knowing possession of a controlled substance

that the Supreme Court’s dicta in Bailey mistakenly treats the difference between general and specific intent as
“reducible to the difference between two mental states.” Johnson, Rethinking the Presumption of Mens Rea, supra note
87, at 790 n.119. As described above, at least one conception of the difference between general and specific intent is
that it delineates between the elements to which a given mental state attaches. See id. at 790-91; supra § “Background.”
171 United States v. Salinas, 763 F.3d 869, 880 (7th Cir. 2014). Ordinarily, “the term ‘knowingly’ merely requires proof
of knowledge of the facts that constitute the offense” and not knowledge of the law or unlawfulness. Bryan v. United
States, 524 U.S. 184, 193 (1998) (emphasis added). However, construction of particular statutes may lead to a different
result based on the analysis described supra, § “Application of Mens Rea to Specific Elements.” For instance, in
Liparota v. United States, the Court determined that a statute prohibiting knowing use of food stamps “in any manner
not authorized” by statute or regulation required a defendant to know “that his conduct was unauthorized or illegal.”
471 U.S. 419, 434 (1985).
172 See United States v. Sablan, 92 F.3d 865, 868 (9th Cir. 1996) (describing legislative history).
173 S. REP. NO. 99-432, at 6 (1986); see United States v. Drew, 259 F.R.D. 449, 459 (C.D. Cal. 2009) (quoting report
language in interpreting CFAA). The notion of intent as conscious object or purpose can also be significant for other
kinds of crimes like homicide, which is federally proscribed in jurisdictionally limited circumstances, and treason. See
Bailey, 444 U.S. at 405.
174 United States v. Jewell, 532 F.2d 697, 702 (9th Cir. 1976).
175 See Global-Tech Appliances, Inc. v. SEB S.A., 563 U.S. 754, 769 (2011) (mentioning that “the Courts of Appeals
. . . all appear to agree” on basic parameters of willful blindness doctrine). The concept, however, is “categorically
different from negligence or recklessness,” United States v. Heredia, 483 F.3d 913, 918 n.4 (9th Cir. 2007) (en banc),
which are discussed in more detail infra.
176 Id. One point of apparent disagreement concerns whether the defendant also must have the “motive in deliberately
failing to learn the truth . . . to give himself a defense in case he should be charged with the crime.” Heredia, 483 F.3d
at 919 (rejecting motive requirement); but see United States v. Davis, 901 F.3d 1030, 1034 (8th Cir. 2018) (stating that
willful blindness instruction “is proper if the evidence supports the inference that the defendant was aware of a high
probability of the existence of the fact in question and purposely contrived to avoid learning all of the facts in order to
have a defense in the event of a subsequent prosecution.” (internal alteration & quotation marks omitted)); see
generally Alexander F. Sarch, Willful Ignorance, Culpability, and the Criminal Law, 88 ST. JOHN’S L. REV. 1023
(2014) (describing disagreement).
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under 21 U.S.C. § 841(a)(1).177 A rationale frequently given for the doctrine is that “persons who
know enough to blind themselves to direct proof of critical facts in effect have actual knowledge
of those facts.”178
Willfully
Beyond “knowingly” and “intentionally,” another of the most commonly used mens rea terms in
federal criminal law is “willfully,”179 which may appear as a standalone term180 or in conjunction
with “knowingly.”181 The term also exemplifies, perhaps better than any other, the non-uniformity
of mental-state requirements under federal law. As the Supreme Court has recognized, the “word
‘willfully’ is sometimes said to be ‘a word of many meanings’ whose construction is often
dependent on the context in which it appears.”182 Other courts have referred to the term more
colorfully as “notoriously slippery” and a “chameleon word.”183 As the National Commission on
Reform of Federal Criminal Laws summarized it, courts “have endowed the requirement of
willfulness with the capacity to take on whatever meaning seems appropriate in the statutory
context,” providing “[p]erhaps the best illustration of the confusion engendered by existing
statutory formulations of the mental element” in federal criminal law.184
In a common formulation, “a ‘willful’ act is one undertaken with a ‘bad purpose,’” meaning that
to act “willfully” requires “knowledge that [one’s] conduct was unlawful.”185 This formulation
distinguishes the term “willfully” from a common conception of “knowingly” under federal law,
as the latter ordinarily requires only knowledge of the facts that constitute an offense.186 The
typical knowledge-of-unlawfulness formulation of “willfully” does not, however, require
knowledge of the precise legal provision or prohibition that has been violated.187 Rather, all that is
required is knowledge that conduct is unlawful “in some general sense.”188

177 See Heredia, 483 F.3d at 917-18 (describing this situation).
178 United States v. Parker, 872 F.3d 1, 14 (1st Cir. 2017) (quoting Global-Tech, 563 U.S. at 766).
179 O’MALLEY, GRENIG, & LEE, supra note 6, § 17:01.
180 E.g., 18 U.S.C. § 924(a)(1)(D) (establishing criminal penalties for those who “willfully” violate certain firearm-
related requirements).
181 E.g., 18 U.S.C. § 1501 (prohibiting “knowingly and willfully” obstructing a federal process server, among other
things).
182 Bryan v. United States, 524 U.S. 184, 191 (1998) (quoting Spies v. United States, 317 U.S. 492, 497 (1943)).
183 United States v. Starnes, 583 F.3d 196, 210 (3d Cir. 2009) (quoting United States v. Ladish Malting Co., 135 F.3d
484, 487-88 (7th Cir. 1998)).
184 See 1 WORKING PAPERS, supra note 73, at 120.
185 Bryan, 524 U.S. at 191.
186 Dixon v. United States, 548 U.S. 1, 5 (2006). As noted above, construction of particular statutes may result in a
definition of “knowingly” that does include knowledge of unlawfulness to some degree, which may be thought of as
more akin to the typical formulation of a willfulness requirement. See supra note 171.
187 See Bryan, 524 U.S. at 195-96 (rejecting argument that willfulness requirement in firearm-related statute
necessitates knowledge of the law, as “knowledge that the conduct is unlawful is all that is required”); Screws v. United
States, 325 U.S. 91, 103, 106 (1945) (Reading willfulness requirement in 18 U.S.C. § 242 as calling for “specific intent
to deprive a person of a federal right made definite by decision or other rule of law” but indicating that defendant does
not need to be “thinking in constitutional terms”).
188 United States v. Starnes, 583 F.3d 196, 210 (3d Cir. 2009); see also United States v. Kosinski, 976 F.3d 135, 154
(2d Cir. 2020) (“As a general matter, a person who acts willfully need not be aware of the specific law that his conduct
may be violating. Rather, knowledge that the conduct is unlawful is all that is required.” (citation and internal quotation
marks omitted)); United States v. Hernandez, 859 F.3d 817, 823 (9th Cir. 2017) (“In this case, the government was
required to show that [the defendant] knew his transportation of firearms . . . was somehow unlawful, even if he did not
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Courts have identified additional “levels of interpretation” of “willfully.”189 In some contexts the
term may merely “denote an act which is intentional, or knowing, or voluntary, as distinguished
from accidental”—in other words, it may be synonymous with other mens rea standards
discussed in this section.190 By contrast, in the context of “highly technical statutes that present[]
a danger of ensnaring individuals engaged in apparently innocent conduct,”191 courts have
recognized a heightened formulation of “willfulness” that requires “proof that the defendant
actually knew of the specific law prohibiting the conduct.”192 For instance, in Cheek v. United
States, the Supreme Court determined that statutory provisions of the tax code criminalizing
willful tax evasion and willful failure to file returns required “actual knowledge of the pertinent
legal duty,” as the complexity of the tax laws “made it difficult for the average citizen to know
and comprehend the extent of the duties and obligations imposed” by those laws.193
Example of Courts’ Construction of Arson Statute, 18 U.S.C. § 81
An example of the complications that may arise in construing federal statutes that require some
level of intentionality or awareness can be found in dueling court constructions of 18 U.S.C.
§ 81.194 That statute prohibits “willfully and maliciously sett[ing] fire to or burn[ing] any
building, structure or vessel,” among other things, in a certain federal jurisdictional context.195 In

know of the specific legal duty, or the particular law, that made it unlawful.”).
189 Starnes, 583 F.3d at 210.
190 Bryan, 524 U.S. at 191 n.12; see, e.g., United States v. Gonsalves, 435 F.3d 64, (1st Cir. 2006) (“Willfulness . . .
means nothing more in this context than that the defendant knew that his statement was false when he made it or . . .
consciously disregarded or averted his eyes from its likely falsity.”). This is the definition of willfulness embraced by
the MPC, which states that a willfulness requirement “is satisfied if a person acts knowingly with respect to the
material elements of the offense, unless a purpose to impose further requirements appears.” MODEL PENAL CODE
§ 2.02(8) (1985). Under federal law, in fact, a requirement of willfulness may even be construed to encompass
recklessness depending on the context. See United States v. Blankenship, 846 F.3d 663, 673 (4th Cir. 2017) (“In
interpreting a variety of criminal statutes, other Circuits have reached the same conclusion: . . . ‘reckless disregard’ still
can—and does—constitute criminal willfulness.”). Recklessness as a mens rea requirement in federal statutes is
discussed in more detail infra.
191 Bryan, 524 U.S. at 194.
192 Starnes, 583 F.3d at 211; see Ratzlaf v. United States, 510 U.S. 135, 149 (1994) (applying stringent formulation of
willfulness requirement to financial anti-structuring laws). In these circumstances, the inclusion of a willfulness
requirement may operate as an exception to the longstanding maxim that “ignorance of the law or a mistake of law is
no defense to criminal prosecution.” United States v. Marshall, 753 F.3d 341, 345 (1st Cir. 2014) (Souter, J.) (quotation
omitted). In other words, where a willfulness requirement necessitates proof that the defendant actually knew of the
legal provision that proscribed his conduct, ignorance of that law may constitute a defense to conviction because it
negates the requisite mens rea. A discussion of these and other defense issues that relate to mens rea can be found
infra, § “Selected Additional Mens Rea Issues in Federal Law.”
193 498 U.S. 192, 200, 202 (1991).
194 See Batey, supra note 7, at 367-71 (describing statute and court opinion construing it as “a particularly clear
example of the definitional possibilities inherent in general intent”).
195 18 U.S.C. § 81. In full, the statute provides:
Whoever, within the special maritime and territorial jurisdiction of the United States, willfully and
maliciously sets fire to or burns any building, structure or vessel, any machinery or building
materials or supplies, military or naval stores, munitions of war, or any structural aids or appliances
for navigation or shipping, or attempts or conspires to do such an act, shall be imprisoned for not
more than 25 years, fined the greater of the fine under this title or the cost of repairing or replacing
any property that is damaged or destroyed, or both.
If the building be a dwelling or if the life of any person be placed in jeopardy, he shall be fined
under this title or imprisoned for any term of years or for life, or both.
Id.
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United States v. M.W., the Tenth Circuit196 construed the statute’s “willfully and maliciously”
mens rea requirement in the case of a student who broke into a school located on an Indian
reservation and set fire to school records in the principal’s office.197 The fire got out of control
and resulted in extensive damage to the school building.198 The district court found the student
guilty of arson under 18 U.S.C. § 81 and, on appeal, the student argued that the statute required
him to have “the intent to burn [the] building,” which he did not have because he only intended to
burn the records.199 The Tenth Circuit applied the MPC approach and determined that (1)
knowledge was sufficient to meet the willfulness requirement, and (2) because burning the
building was a result element, the student could be convicted if he was “aware that it [was]
practically certain that his conduct” would cause that result.200 In other words, the Tenth Circuit
construed the “willfully and maliciously” term as requiring only knowledge—i.e., awareness to a
practical certainty—that conduct would result in setting fire to a building and upheld the student’s
conviction based on the lower court’s finding that he had such awareness.201
By contrast, in United States v. Doe (R.S.W.), the Ninth Circuit construed the same statute in
similar factual circumstances as requiring neither intent to burn a building nor “knowledge this
would be the probable consequence of the defendant’s act.”202 Rather, according to the court, all
that the “willfully and maliciously” term required was general intent to do the act that caused a
building to burn, i.e., “that the defendant set the fire intentionally and without justification or
lawful excuse.”203 In reaching this conclusion, the court expressly rejected reliance on the MPC,
observing that because the mens rea term was drawn from the common law definition of arson,
the court should assume that Congress “knew how the common law defined that phrase” and
“intended to adopt the [general-intent] meaning that common law gave” it when enacting 18
U.S.C. § 81.204 In dissent, one judge argued that the court’s construction effectively turned the
statute into a strict liability offense, as the majority mistakenly applied a standard of intentionality
“not to the proscribed conduct of setting fire to a building, but to [the defendant’s] mental state
toward setting [items in the building] aflame.”205
As these two cases reflect, mens rea terms like “intentionally,” “knowingly,” and “willfully” may
overlap or blend into each other, and judicial interpretations of such terms may differ markedly
even as applied to the same statute under very similar factual circumstances. Thus, in M.W., the
court viewed “willfully and maliciously” as requiring only knowledge, but it treated that
knowledge requirement as extending to the result of a building being burned, while in R.S.W., the
court purported to treat “willfully and maliciously” as synonymous with intention but concluded
that intention (in the sense of voluntariness) with respect to the act of lighting the fire was
sufficient to meet the statute’s mens rea requirement.

196 This report references a significant number of decisions by federal appellate courts of various regional circuits. For
purposes of brevity, references to a particular circuit in the body of this report (e.g., the Fifth Circuit) refer to the U.S.
Court of Appeals for that particular circuit.
197 890 F.2d 239, 239 (10th Cir. 1989).
198 Id.
199 Id. at 240.
200 Id. at 240-41.
201 Id. at 241.
202 136 F.3d 631, 635 (9th Cir. 1998).
203 Id. at 635.
204 Id. at 634, 636.
205 Id. at 637-38 (Fletcher, J., dissenting).
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Recklessly and Negligently
Though the mens rea concepts of recklessness and negligence are much less central in federal
criminal law than are concepts of intention or knowledge,206 some federal criminal provisions do
utilize them.207 In general, recklessness and negligence are distinct from other mens rea standards
in that they focus on risk.208 Nonetheless, recklessness shares with higher forms of mens rea a
requirement of subjective awareness, while negligence is often understood to establish an
objective standard that arguably takes it out of the realm of a true “mental-state” requirement
altogether.209
Recklessly
According to the Supreme Court, the “dominant formulation” of a mens rea requirement of
recklessness is that one “consciously disregard[s] a substantial risk” of harm.210 This formulation
is drawn from the MPC, which defines recklessness as conscious disregard of “a substantial and
unjustifiable risk” that an element exists or will result from one’s conduct.211 It appears that
federal courts largely use this definition, or one that is substantially similar, in construing federal
statutes that contain the term “reckless” or “reckless disregard.”212 As the definition suggests,
criminal recklessness under federal law generally requires subjective awareness of a risk and
deliberate disregard of it, i.e., “the intentional taking of a risk that might result in harm,”213
though there may be some variation among courts and across statutes as to whether awareness of

206 See O’MALLEY, GRENIG, & LEE, supra note 6, § 17:01 (stating that concepts of recklessness and negligence “have
little relevance in federal criminal law”); THIRD CIRCUIT JURY INSTRUCTIONS, supra note 157, ch. 5, p. 36
(“‘Recklessly’ is not frequently used to define the state of mind requirement in federal criminal statutes.”).
207 E.g., 18 U.S.C. § 1591(a) (prohibiting, among other things, knowingly recruiting a person “in reckless disregard of
the fact” that force or other proscribed means will be used to cause the person to engage in a commercial sex act); 18
U.S.C. § 755 (establishing criminal penalties for one who “negligently suffers [a federal prisoner] to escape,” among
other things).
208 See, e.g., MODEL PENAL CODE §§ 2.02(2)(c)-(d) (1985).
209 E.g., id.; see supra note 6 and accompanying text; Godwin v. United States, 441 F. Supp. 3d 1243, 1257 n.9 (M.D.
Ala. 2020) (“The basic distinction between recklessness and negligence is that an actor is criminally negligent when he
should have been aware of the risk but was not, while recklessness requires that the defendant actually be aware of the
risk but disregard it.” (alteration, citation, and internal quotation marks omitted)).
210 Voisine v. United States, 136 S. Ct. 2272, 2278 (2016) (quoting MODEL PENAL CODE § 2.02(2)(c) (1985)).
211 MODEL PENAL CODE § 2.02(2)(c) (1985).
212 E.g., Farmer v. Brennan, 511 U.S. 825, 836-37 (1994); United States v. Fagatele, 944 F.3d 1230, 1239 (10th Cir.
2019); United States v. Rodriguez, 880 F.3d 1151, 1159-61 (9th Cir. 2018); Anderson v. Kingsley, 877 F.3d 539, 543-
45 (4th Cir. 2017); United States v. Mottweiler, 82 F.3d 769, 771 (7th Cir. 1996); Macleod, supra note 152, at 513 n.54
(“[T]he MPC recklessness ‘formulation is substantially the same as the formulations of recklessness in federal and state
criminal codes and judicial decisions.’” (quoting LARRY ALEXANDER & KIMBERLY KESSLER FERZAN, CRIME AND
CULPABILITY: A THEORY OF CRIMINAL LAW 35 (2009)).
213 Anderson, 877 F.3d at 545; see Farmer, 511 U.S. at 836-37 (“The criminal law . . . generally permits a finding of
recklessness only when a person disregards a risk of harm of which he is aware.”). The MPC further defines a
“substantial and unjustifiable” risk as a risk “of such a nature and degree that, considering the nature and purpose of the
actor's conduct and the circumstances known to him, its disregard involves a gross deviation from the standard of
conduct that a law-abiding person would observe in the actor's situation.” MODEL PENAL CODE § 2.02(2)(c) (1985).
Some federal courts may include this further definition in jury instructions as well, recognizing that although
recklessness requires subjective awareness, “the nature of the risk is measured by an objective standard.” United States
v. Rodriguez, 880 F.3d 1151, 1161 (9th Cir. 2018) (emphasis added); but cf. THIRD CIRCUIT JURY INSTRUCTIONS, supra
note 157, at ch. 5, pp. 35-36 (noting that although “the Third Circuit does not seem to have included this further
definition in its few cases discussing recklessly, the trial court could include it in an instruction on recklessly if it thinks
a further explanation is necessary”).
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facts and circumstances giving rise to a risk is sufficient to establish recklessness in the absence
of awareness of the risk itself.214
Recklessness thus differs from a mens rea standard of “knowledge” primarily in regard to the
degree of certainty of a circumstance or outcome of which a defendant is aware—in the MPC
formulation that is sometimes used by federal courts, knowledge connotes awareness of a high
probability or to a practical certainty; recklessness, by contrast, focuses on awareness of some
lesser degree of risk.215 For example, the Fourth Circuit in United States v. Carr considered a
federal statute prohibiting intentionally damaging or destroying certain buildings by means of fire
or an explosive and causing the death of any person.216 The case required the court to distinguish
between a knowing and reckless state of mind with respect to the death that occurred for
sentencing purposes.217 The district court found that the defendant, who set fire to an apartment
building resulting in the death of an occupant, was “recklessly indifferent to whether people
would be in the apartment building” because the mailboxes, gas meters, and cars out front made it
“obvious” the structure was occupied.218 The district court viewed this “reckless indifference” as
“equat[ing] to knowledge” and thus refused to consider a lower sentence that could apply for
recklessly causing death.219 On appeal, the Fourth Circuit rejected the lower court’s conflation of
recklessness and knowledge, making clear that although both standards “require a subjective
awareness of risk on the part of the actor,” the “degree of the risk that the actor is aware of” (i.e.,
a substantial risk versus practical certainty) distinguishes the two.220 The court held that, although
the lower court’s findings regarding indicia of occupancy like mailboxes “certainly support[ed] a
finding of recklessness,” its failure to make a finding on the question of whether the evidence
supported the higher standard of knowledge (i.e., whether he acted “with an awareness that death
was practically certain to result”) was erroneous.221
Given that the primary distinction between common definitions of knowledge and recklessness
focuses on the degree of risk of a particular outcome, at least one circuit has held that, in
determining the sufficiency of the evidence, “a finding that an accused acted recklessly may be
enough to sustain a jury verdict” pursuant to a statute that requires knowledge “because a jury

214 Compare Rodriguez, 880 F.3d at 1160 (making clear that for purposes of statutory prohibition on transporting an
illegal alien for financial gain, defendant must not merely be aware of facts “from which the inference of the risk at
issue could be drawn” but must “actually draw the inference”), with United States v. Kendrick, 682 F.3d 974, 984 (11th
Cir. 2012) (stating that “reckless disregard” term in separate subsection of same statute “means to be aware of, but
consciously and carelessly ignore, facts and circumstances clearly indicating that” element exists); see also United
States v. Carson, 870 F.3d 584, 603 (7th Cir. 2017) (recognizing that “[o]ther courts to have considered the question
have concluded that the phrase ‘reckless disregard’ in [a] statute [proscribing sex-trafficking activities] requires only an
awareness of facts and circumstances that give rise to a risk of a . . . violation, not an awareness of the risk itself”).
215 See supra notes 168-169; United States v. Carr, 303 F.3d 539, 547 (4th Cir. 2002) (“From the definitions we see that
‘knowing’ and ‘reckless’ states of mind both require a subjective awareness of risk on the part of the actor. The
difference lies in the degree of the risk that the actor is aware of.”).
216 303 F.3d at 540 (addressing 18 U.S.C. § 844(i)).
217 Id. at 540-41. The state-of-mind distinction was relevant by virtue of the United States Sentencing Guidelines,
which in an application note encouraged a downward departure from the applicable sentencing range if “the defendant
did not cause the death intentionally or knowingly” but caused it through “recklessness or negligence.” Id. at 545-46
(citing U.S. SENT’G GUIDELINES MANUAL § 2A1.1 cmt. n.1 (U.S. SENT’G COMM’N 2001)). A separate application note
defined the term “reckless” in a similar fashion as the MPC. Id.
218 Id. at 544, 545.
219 Id.
220 Id. at 546-47.
221 Id. at 548 (citation and internal quotation marks omitted).
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may properly infer the requisite intent.”222 Any boundary between the two levels of culpability
may also be further blurred in some instances—for example, the Sixth Circuit has interpreted a
statute proscribing (among other things) knowing failure to disclose information required under
Title I of the Employee Retirement Income Security Act of 1974 as requiring only “proof of a
voluntary conscious failure to disclose without ground for believing that such non-disclosure is
lawful, or with reckless disregard for whether or not it is lawful.”223 In other words, a “knowing”
mens rea requirement may be construed in particular contexts to require only recklessness with
respect to a circumstance or result, as may a “willfulness” requirement in some cases.224
Negligently
Negligence is a concept that will likely be most familiar to those acquainted with tort law.225 It
can also have criminal applications, although negligence as a federal mens rea standard is less
prevalent than other terms discussed in this report.226 At the most basic level, negligence
embodies (1) conduct that is “judged by an objective (reasonable man) standard,” and (2) some
“degree of risk which the defendant’s conduct must create.”227 One conception of negligence in
the criminal context, reflected in the MPC, is that the defendant “should be aware” of a risk that
the statutory element at issue exists or will result from his conduct.228 According to this view, the
“basic distinction” between recklessness and negligence is that a defendant “is criminally
negligent when he should have been aware of the risk but was not, while recklessness requires
that the defendant actually be aware of the risk but disregard it.”229 Whether a defendant “should
have been aware” is, in turn, judged by the objective standard of a reasonable person.230 The MPC
approach to negligence also emphasizes that the risk must be “substantial and unjustifiable,” i.e.,
the risk must be “of such a nature and degree” that failure to perceive it “involves a gross
deviation from the standard of care that a reasonable person would observe in the actor’s
situation.”231 These elaborations may be said to embody a heightened standard of “gross” or
“criminal” negligence, as distinguished from the ordinary negligence typically sufficient for civil
liability that, in one representative formulation, requires only “doing something which a
reasonably prudent person would not do, or . . . failing to do something which a reasonably
prudent person would do.”232

222 United States v. Adamson, 700 F.2d 953, 962 (5th Cir. 1983) (emphasis omitted); see also United States v. Ladish
Malting Co., 135 F.3d 484, 488 (7th Cir. 1998) (“Criminal recklessness may be so close to actual knowledge that proof
of one suffices for proof of the other[.]”).
223 United States v. Krimsky, 230 F.3d 855, 859 (6th Cir. 2000) (quoting United States v. S & Vee Cartage Co., Inc.,
704 F.2d 914, 919 (6th Cir.1983)).
224 See supra note 190.
225 See LAFAVE, supra note 6, § 5.4(a) (indicating that negligence “will usually do for tort liability”).
226 See supra note 157 and accompanying text; William S. Laufer, Culpability and the Sentencing of Corporations, 71
NEB. L. REV. 1049, 1072 (1992) (“referencing “near complete absence of negligence” in Title 18 of U.S. Code).
227 LAFAVE, supra note 6, § 5.4(a).
228 United States v. Zats, 298 F.3d 182, 189 (3d Cir. 2002) (quoting MODEL PENAL CODE § 2.02(2)(d) (1985)).
229 Godwin v. United States, 441 F. Supp. 3d 1243, 1257 n.9 (M.D. Ala. 2020) (citation and internal quotation marks
omitted).
230 See LAFAVE, supra note 6, § 5.4(a)(2) (“All that negligence requires is that [a person] ought to have been aware of
[the risk] (i.e., that a reasonable man would have been aware of it).”).
231 MODEL PENAL CODE § 2.02(2)(d) (1985).
232 United States v. Pruett, 681 F.3d 232, 241 (5th Cir. 2012). The MPC and Pruett formulations of ordinary and so-
called gross negligence are far from the only ones—as one commentator has noted, “[t]raditional criminal law doctrine
. . . does not employ or emphasize any single conception of negligence” but rather “contains a variety of doctrines that
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Some have suggested that an “ordinary” negligence standard is inappropriate for imposition of
criminal liability, arguing that criminalizing mere failure to exercise ordinary care has “limited
deterrent value” and is “fundamentally unfair.”233 Nevertheless, “the notion that criminal liability
might extend in special circumstances to simple negligence . . . is a surprisingly long-standing
feature of federal statute, with a similarly long history of favorable treatment by the Supreme
Court.”234 As such, to the limited extent negligence is employed in federal law as a mens rea
standard for criminal prohibitions, it may be interpreted as requiring only ordinary negligence in
the absence of an indication of legislative intent to impose a higher standard.235 However, there is
no uniform conception of negligence in federal criminal law. As with the other mens rea
standards discussed in this report, formulations may vary by court or statute236 and may overlap
with conceptions of more culpable mental states like recklessness. For instance, 18 U.S.C. § 1112
defines involuntary manslaughter as “the unlawful killing of a human being without malice . . . in
the commission in an unlawful manner, or without due caution and circumspection, of a lawful
act which might produce death.”237 Several courts have interpreted the statute as imposing a mens
rea requirement of “gross negligence” but have defined that requirement in at least partially
subjective terms.238
Example of Courts’ Construction of Occupational Safety & Health Act, 29 U.S.C.
§ 666(e)
An illustrative example of the dividing lines between recklessness, negligence, and higher levels
of culpability in federal criminal law can be found in a Seventh Circuit decision addressing the
Occupational Safety & Health Act (OSHA), which establishes (among other things) criminal
penalties for employers who “willfully violate[]” health and safety standards or regulations such
that death of an employee results.239 In United States v. Ladish Malting Co., the Seventh Circuit
reviewed jury instructions that defined “willfully” as “knowingly and voluntarily” in “reckless

could be broadly classified as involving negligence[.]” Kenneth W. Simons, Dimensions of Negligence in Criminal and
Tort Law, 3 THEORETICAL INQUIRIES L. 283, 288 n.7 (2002).
233 Brigid Harrington, A Proposed Narrowing of the Clean Water Act’s Criminal Negligence Provisions: It’s Only
Human?, 32 B.C. ENV’T AFFS. L. REV. 643, 657 (2005); see Leslie Yalof Garfield, A More Principled Approach to
Criminalizing Negligence: A Prescription for the Legislature, 65 TENN. L. REV. 875, 910-11 (1998) (identifying a
“prevailing view that punishing ordinary negligent behavior generally should be avoided” as unjust and ineffective).
Sometimes the argument takes on a constitutional dimension. But see United States v. Hanousek, 176 F.3d 1116, 1122
(9th Cir. 1999) (rejecting argument that ordinary negligence standard in Clean Water Act violates due process).
234 Brook B. Andrews, Mens Rea in the CWA, S.C. LAW., July 2016, at 21, 23.
235 See Pruett, 681 F.3d at 243 (agreeing with Ninth and Tenth Circuits that ordinary negligence is sufficient for
misdemeanor Clean Water Act provision); United States v. Alvarez, 809 F. App’x 562, 567-68 (11th Cir. 2020) (per
curiam) (recognizing that plain language of Seaman’s Manslaughter Statute “criminalizes simple negligence”).
236 E.g., 42 U.S.C. § 7413(c)(4) (applying to one who “negligently places another person in imminent danger of death
or serious bodily injury”).
237 18 U.S.C. § 1112(a). Involuntary manslaughter may also occur through “the commission of an unlawful act not
amounting to a felony” or in the commission “in an unlawful manner” of a lawful act which might produce death. Id.
The offense is limited to conduct occurring within the special maritime and territorial jurisdiction of the United States.
Id. § 1112(b).
238 See United States v. Bolman, 956 F.3d 583, 586 (8th Cir. 2020) (defining gross negligence for purposes of
involuntary manslaughter as “wanton or reckless disregard for human life” with knowledge that the defendant’s
“conduct was a threat to the lives of others or having knowledge of such circumstances as could reasonably have
enabled him to foresee the peril to which his act might subject others”); United States v. Pineda-Doval, 614 F.3d 1019,
1038-39 (9th Cir. 2010) (similar).
239 29 U.S.C. § 666(e).
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disregard” of relevant requirements, further defined “reckless disregard” in part as “having
knowledge” of a hazardous working condition, and defined “having knowledge” of such
condition to mean that the employer “knew or should have known of the hazardous condition.”240
In other words, the instructions permitted a conviction if the jury concluded that the employer
“should have known” of a dangerous condition and “reasonably should have known” that the
condition violated federal requirements.241
The appellate court concluded that these instructions regarding the requisite mens rea with respect
to the hazardous working condition at issue were erroneous.242 The court determined that defining
“knowledge” in terms of what one “knew or should have known” improperly rendered the
statutory willfulness requirement synonymous with ordinary negligence.243 According to the
Seventh Circuit, the instructions “equated willfulness with knowledge, watered down knowledge
to recklessness, defined recklessness as negligence, and used the civil rather than the criminal
approach to negligence” by failing to add the “standard gloss” of a heightened negligence
standard applicable in criminal cases.244 The court stated it was “essential to preserve the
difference” between these standards by requiring that knowledge mean actual knowledge or
willful blindness and that recklessness mean actual awareness of a risk, lest “knowledge,
recklessness, criminal negligence, and civil negligence . . . merge into a single mental state[.]”245
As such, the court concluded that “[t]ransforming” willfulness to ordinary negligence was
“inappropriate both in principle and for [OSHA] in particular.”246
Other Mens Rea Standards
As described previously, because the U.S. Code does not generally employ the standardized
culpability rules and definitions found in the MPC, federal mens rea requirements are largely
statute-specific.247 Congress has also, at times, used state-of-mind language in particular statutes
that either does not clearly signal which level of culpability is intended or that appears to establish
a state-of-mind requirement that does not fit neatly into one of the categories described above,
leaving courts to attempt to interpret the language in a way that comports with congressional
intent. As a result, specific federal crimes, as defined or as interpreted by the federal courts, may
bear mental-state requirements that appear to blend components of more than one standard.248
For instance, several federal statutes prohibit conduct engaged in with either intent or knowledge,
or with “reason to believe,” “reasonable cause to believe,” or “reason to know” of some attendant
circumstance or result.249 Court decisions have displayed a degree of confusion as to where this

240 135 F.3d 484, 486-87 (7th Cir. 1998). The employer contested “the requirement that it act ‘knowingly’ with respect
to the facts—that is, that the firm be aware” of the hazardous condition. Id. at 487.
241 Id. at 487.
242 Id. at 487-88.
243 Id. at 488.
244 Id.
245 Id.
246 Id.
247 See supra notes 152-154 and accompanying text.
248 E.g., 49 U.S.C. § 5124(b) (defining “knowingly” for purposes of criminal violations of restrictions on transportation
of hazardous material as “actual knowledge of the facts giving rise to the violation” or that “a reasonable person acting
in the circumstances and exercising reasonable care would have that knowledge”).
249 See 18 U.S.C. § 794(a) (proscribing delivery of defense information to foreign government or actor “with intent or
reason to believe that it is to be used to the injury of the United States or to the advantage of a foreign nation”); id. §
1521 (proscribing filing false lien against federal officer or employee “knowing or having reason to know” of falsity);
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language falls on the continuum between actual knowledge and an objective, “reasonable person”
standard closer to negligence. The Tenth Circuit, for instance, construed a statute that prohibits
possession or distribution of listed chemicals “knowing, or having reasonable cause to believe,”
they will be used to manufacture a controlled substance as involving a “subjective inquiry” that
“requires scienter to be evaluated through the lens of th[e] particular defendant, rather than from
the prospective of a hypothetical reasonable man.”250 In other words, the court viewed the mens
rea standard of “reasonable cause to believe” as “akin to actual knowledge,”251 requiring
subjective knowledge “or something close to it” that the chemical at issue would be used to
manufacture a controlled substance.252 However, the court in a subsequent case addressing a
statute that proscribes filing a false lien against a federal officer or employee “knowing or having
reason to know” of its falsity,253 interpreted the statute as permitting conviction “if a reasonable
person who possessed the information possessed by the defendant would have the requisite
knowledge of falsity,” i.e., the court treated the mens rea standard of “knowing” or “having
reason to know” as having “both a subjective component (that is, what information this particular
defendant had) and an objective component (what a reasonable person would infer from that
information).”254 In dicta, the court distinguished language from its earlier decisions that
suggested a different reading and maintained that prior holdings were consistent with the
proffered interpretation.255
Other circuits have agreed with a conception of “reasonable cause to believe” as a hybrid
subjective/objective standard, emphasizing that the inquiry “turns on the facts actually known by
the defendant in a particular case—facts from which the jury can infer that any reasonable person
in the defendant's position would have had to know . . . .”256 At least one district court has made
clear, however, that a similar standard in a statute prohibiting delivery of defense information to a
foreign government or actor “with intent or reason to believe that it is to be used” in a particular
way is not a negligence standard, as it requires the jury to “find that defendant personally and
subjectively believed or should have believed” the information was to be used for the prohibited
purpose.257
Selected Additional Mens Rea Issues in Federal Law
In addition to the questions of what mental states are required for federal offenses and what they
mean, distinct issues arise for certain classes of offenses and species of federal criminal
liability—specifically, inchoate crimes, such as attempt and conspiracy, and corporate liability.

21 U.S.C. § 841(c)(2) (proscribing possession or distribution of listed chemicals “knowing, or having reasonable cause
to believe,” they will be used to manufacture controlled substance).
250 United States v. Saffo, 227 F.3d 1260, 1268-69 (10th Cir. 2000).
251 Id. at 1269.
252 United States v. Truong, 425 F.3d 1282, 1289 (10th Cir. 2005).
253 United States v. Williamson, 746 F.3d 987, 994 (10th Cir. 2014).
254 Id.
255 Id. at 994 n.2.
256 United States v. Munguia, 704 F.3d 596, 603 (9th Cir. 2012) (quoting United States v. Johal, 428 F.3d 823, 828 (9th
Cir. 2005)) (emphasis omitted); see also United States v. Galvan, 407 F.3d 954, 957 (8th Cir. 2005) (concluding that
jury instruction treating “reasonable cause to believe” as akin to actual knowledge would incorrectly render the phrase
redundant).
257 United States v. Mallory, 343 F. Supp. 3d 570, 576 (E.D. Va. 2018).
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Mental state considerations also can be relevant to an alleged offender’s defense to criminal
liability.
Inchoate Crimes
Under federal law, it is a separate crime to conspire to commit any other federal crime, i.e., to
agree with another to commit the crime and typically to take some overt action in furtherance of
its commission.258 Likewise, though there is no general federal attempt provision, attempts to
commit many of the most common federal crimes are proscribed in individual statutes.259 These
crimes, which existed at common law, are said to be “inchoate” in the sense that they are “crimes
on their way to becoming other crimes unless stopped or abandoned.”260 Because these offenses,
in a general sense, encompass the contemplation or objective of committing another crime, they
are sometimes said to require a “heightened mental state” that, in the words of the Supreme
Court, “separates criminality itself from otherwise innocuous behavior.”261 The MPC reflects this
notion in its conspiracy and attempt provisions by generally requiring the highest level of
culpability, “purpose”—to promote or facilitate commission of an offense (in the case of
conspiracy) or to engage in conduct or cause a result (in the case of attempt).262
In federal law, the mens rea for inchoate crimes is often couched in the language of “specific
intent.”263 More precisely, an attempt to commit a federal crime has been framed as taking “a
substantial step towards completion of the offense” while acting “with the specific intent to
commit the underlying crime,”264 and a conspiracy, among other things, “requires proof of

258 See CRS Report R41223, Federal Conspiracy Law: A Brief Overview, by Charles Doyle. 18 U.S.C. § 371 generally
proscribes conspiracies to commit other federal crimes, and dozens of other federal statutes separately criminalize
conspiracies to engage in specific kinds of misconduct. Id. Though Section 371 carries an overt-act requirement, some
of the more specific conspiracy provisions do not. See id. at 2 (“Section 371 and a few others require at least one
conspirator to take some affirmative step in furtherance of the scheme. Many have no such explicit overt act
requirement.”).
259 CRS Report R42001, Attempt: An Overview of Federal Criminal Law, by Charles Doyle.
260 Id. at 13.
261 United States v. Bailey, 444 U.S. 394, 405 (1980).
262 See MODEL PENAL CODE §§ 5.01, 5.03 (1985). The MPC’s attempt provision has “two exceptions” to the purpose
requirement: first, “the culpability otherwise required for commission of the [attempted] crime” is all that is required
for a circumstance element, and for offenses with a result element, either purpose or “a belief that the result will occur
without further conduct on the actor’s part” is sufficient. Id. § 5.01 explanatory note.
263 E.g., United States v. Berckmann, 971 F.3d 999, 1003 (9th Cir. 2020) (“[A]ttempt crimes always require specific
intent.”); United States v. Childress, 58 F.3d 693, 707 (D.C. Cir. 1995) (“[I]t is clear that conspiracy is a ‘specific
intent’ crime.”). Though not technically inchoate, 18 U.S.C. § 2(a) also extends federal criminal liability to anyone who
“aids, abets, counsels, commands, induces or procures” the commission of an offense. Such accomplice or “aiding and
abetting” liability requires an affirmative act in furtherance of the offense and “inten[t] to facilitate that offense’s
commission,” i.e., participation in the underlying crime as “something that [the accomplice] wishes to bring about.”
Rosemond v. United States, 572 U.S. 65, 76-77 (2014). In other words, aiding and abetting liability may be thought of
as requiring a specific intent to advance the offense at issue through, at minimum, active participation “with full
knowledge of the circumstances constituting the charged offense.” Id. (quoting Nye & Nissen v. United States, 336
U.S. 613, 619 (1949)); see also United States v. Gaviria, 116 F.3d 1498, 1535 (D.C. Cir. 1997) (“The elements of
aiding and abetting an offense are (1) the specific intent to facilitate the commission of a crime by another; (2) guilty
knowledge (3) that the other was committing an offense; and (4) assisting or participating in the commission of the
offense.”).
264 United States v. Cote, 504 F.3d 682, 687 (7th Cir. 2007); see also United States v. Gracidas-Ulibarry, 231 F.3d
1188, 1192 (9th Cir. 2000) (recognizing “the doctrine that the crime of attempt requires a showing of specific intent
even if the crime attempted does not” (internal quotation marks omitted)).
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specific intent to further the conspiracy’s objective.”265 Given the multiple and sometimes
indeterminate meanings and usages of the term “specific intent,”266 however, federal courts may
disagree on what is required to prove the mental state for an inchoate crime in a particular
statutory context. For instance, 8 U.S.C. § 1326 criminalizes reentry and attempted reentry into
the United States by aliens who have been removed and lack express permission from the
Attorney General to reapply for admission to the country.267 The federal courts of appeals
generally agree that prohibited reentry under the statute is a general intent crime—i.e., one must
have an intent to enter but does not need to intend to enter unlawfully (in other words, without the
permission of the Attorney General).268
Courts are split, however, on the requisite mental state for attempted reentry under Section 1326.
The Ninth Circuit has reasoned that consistent with the common law meaning of “attempt,”
which requires a specific intent to commit the underlying crime, attempted reentry under Section
1326 requires, among other things, that “the defendant had the purpose, i.e., conscious desire, to
reenter the United States without the express consent of the Attorney General.”269 Yet other
circuits have diverged from this interpretation. For example, the Second Circuit concluded in
United States v. Rodriguez that because Section 1326 establishes a crime unknown at common
law, the “words in the statute are liberated from their common law meanings.”270 As such, based
on the perceived “clarity of the statutory language” and considerations of statutory purpose, the
court in Rodriguez determined that Section 1326 requires only intent to reenter, that there is “no
specific intent requirement for attempted reentry,” and the government is not obligated to
establish a defendant’s mental state with respect to lack of consent or permission.271 The Second
Circuit framed this conclusion as a rejection of the proposition that Section 1326’s attempt
provision incorporates a specific intent requirement,272 though at least one other circuit has

265 Childress, 58 F.3d at 708. One prominent treatise notes likely confusion where the objective of the conspiracy is a
separate crime, “for under such circumstances the mental state for that crime must also be taken into account.”
LAFAVE, supra note 6, § 12.2(c)(2). Put differently, “in order to sustain a judgment of conviction on a charge of
conspiracy to violate a federal statute, the Government must prove at least the degree of criminal intent necessary for
the substantive offense itself.” United States v. Feola, 420 U.S. 671, 686 (1975); see United States v. Brooks, 681 F.3d
678, 699 (5th Cir. 2012) (“Conspiracy actually has two intent elements—intent to further the unlawful purpose and the
level of intent required for proving the underlying substantive offense.”). As noted in an MPC comment, the
implication of a specific intent requirement for conspiracy appears to be that “when recklessness or negligence
suffices” for a result element of a substantive crime, “there could not be a conspiracy to commit that crime.” MODEL
PENAL CODE § 5.03 cmt. at 408 (1985).
266 See supra notes 31-35 and accompanying text.
267 8 U.S.C. § 1326(a).
268 See United States v. Carlos-Colmenares, 253 F.3d 276, 277-78 (7th Cir. 2001) (collecting cases).
269 Gracidas-Ulibarry, 231 F.3d at 1196.
270 416 F.3d 123, 126 (2d Cir. 2005). The court also held that “nothing in the plain language of the statute or in its
legislative history” suggested that “Congress intended to impose a heightened mens rea requirement in cases of
attempted reentry.” Id. at 127.
271 Id. at 128; see also United States v. Morales-Palacios, 369 F.3d 442, 449 (5th Cir. 2004) (“[I]n proving an attempted
illegal reentry it is sufficient that the government demonstrates that a previously deported alien knowingly intended to
reenter the United States—general intent with respect to the actus reus of the crime[.]”).
272 In a subsequent case, the Ninth Circuit asserted that an intervening Supreme Court decision, United States v.
Resendiz-Ponce, 549 U.S. 102 (2007), supported its view because it appeared to recognize that Section 1326
“incorporates the common law meaning of attempt.” United States v. Argueta-Rosales, 819 F.3d 1149, 1160 (9th Cir.
2016). The Supreme Court has not directly addressed the circuit split regarding Section 1326’s attempt provision,
however.
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appeared to treat attempted reentry as “a specific intent crime” while still construing the requisite
intent as extending only to “achiev[ing] entry into the United States.”273
With regard to conspiracy, the so-called “Pinkerton doctrine” (in reference to a famous Supreme
Court case) actually provides somewhat of a mens rea exception for separate substantive offenses
committed in the course of a conspiracy. Under the doctrine, criminal liability is extended “to a
conspirator for a coconspirator’s substantive offenses ‘when they are reasonably foreseeable and
committed in furtherance of the conspiracy.’”274
Corporate Liability
Many federal criminal statutes apply to “whoever” or to any “person” who engages in prohibited
conduct.275 Title 1 of the U.S. Code provides that unless the context of an Act of Congress
indicates otherwise, “the words ‘person’ and ‘whoever’ include corporations, companies,
associations, firms, partnerships, societies, and joint stock companies, as well as individuals.”276
As such, corporate entities generally may commit, and be prosecuted for, federal criminal
offenses, which raises the question of how legal entities that can act only through individuals can
themselves be considered to have committed criminal conduct with the requisite mens rea. This
question is one on which federal law deviates from the approach of the MPC. Under federal law,
corporate criminal liability extends to offenses committed by a corporate officer, employee, or
agent if acting within the scope of his or her authority at least partly for the benefit of the
corporation.277 Where these conditions are met, the mens rea of the officer, employee, or agent
engaging in the proscribed conduct is imputed to the entity for purposes of criminal liability,278
even if the entity’s policies or compliance program deter such activity.279
A distinct issue “arises when no single employee possesses the requisite mens rea necessary for
the offense but a number of employees have, together, committed the unlawful act.”280 In this
circumstance, at least one circuit has endorsed a theory of “collective” knowledge by which the

273 United States v. De Leon, 270 F.3d 90, 92 (1st Cir. 2001).
274 United States v. Henry, 984 F.3d 1343, 1355 (9th Cir. 2021) (quoting United States v. Long, 301 F.3d 1095, 1103
(9th Cir. 2002)); United States v. Hernandez-Roman, 981 F.3d 138, 144 (1st Cir. 2020) (“[I]t is well-established that,
by virtue of the jury’s guilty verdict as to the conspiracy . . . , the defendant became substantively liable for the
foreseeable acts of his coconspirators in furtherance of the conspiracy.”).
275 CRS Report R43293, Corporate Criminal Liability: An Overview of Federal Law, by Charles Doyle.
276 1 U.S.C. § 1. Individual statutes may also specifically define the entities to which they apply. E.g., 18 U.S.C.
§ 1961(3) (specifying that “‘person’ includes any individual or entity capable of holding a legal or beneficial interest in
property”).
277 See, e.g., United States v. Grayson Enters., Inc., 950 F.3d 386, 407 (7th Cir. 2020) (“To prove [the company’s]
liability, the government needed to prove beyond a reasonable doubt that (1) an offense was committed by [the
company’s] agent, (2) in committing the offense, the agent intended, at least in part, to benefit [the company], and (3)
the agent acted within his authority.”); United States v. Oceanic Illsabe Ltd., 889 F.3d 178, 195 (4th Cir. 2018) (“[A]
corporation is liable for the criminal acts of its employees and agents done within the scope of their employment with
the intent to benefit the corporation.”). It is not necessary that the actions actually benefitted the entity, nor must the
employee or agent have been acting solely for the entity’s benefit. United States v. Automated Med. Laboratories, Inc.,
770 F.2d 399, 407 (4th Cir. 1985).
278 E.g., United States v. Philip Morris USA Inc., 566 F.3d 1095, 1118 (D.C. Cir. 2009) (“Because a corporation only
acts and wills by virtue of its employees, the proscribed corporate intent depends on the wrongful intent of specific
employees.”).
279 E.g., United States v. Ionia Mgmt. S.A., 555 F.3d 303, 310 (2d Cir. 2009); United States v. Potter, 463 F.3d 9, 25-26
(1st Cir. 2006). Such policies or programs may be relevant, however, to whether an agent or employee was acting in the
scope of his or her duties. Potter, 463 F.3d at 26.
280 Erin L. Sheley, Tort Answers to the Problem of Corporate Criminal Mens Rea, 97 N.C. L. REV. 773, 782 (2019).
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scienter of individual employees may be aggregated.281 Other courts have been dubious of this
theory, particularly as applied to culpability standards beyond knowledge.282
The MPC takes a different approach to corporate criminal liability (and, accordingly, mens rea).
Section 2.07 of the MPC limits corporate liability for most kinds of crimes to situations where
“the offense was authorized, requested, commanded, performed or recklessly tolerated by the
board of directors or by a high managerial agent acting in behalf of the corporation within the
scope of his office or employment.”283 This “inner circle” approach to corporate liability has been
criticized by some as underinclusive, given modern-day corporate realities.284
Defenses
A defendant’s mental state can be relevant to his or her asserted defense to criminal liability in
several respects, depending on the nature of the defense at issue. In one regard, affirmative
defenses such as self-defense and necessity have their own mental components that are separate
from the mens rea required for commission of the charged crime. For instance, the Tenth Circuit’s
formulation of the requirements for self-defense as a defense to a federal homicide charge
includes that the defendant “reasonably believes that he is in imminent danger of death or great
bodily harm, thus necessitating an in-kind response.”285 In other words, even where the defendant
indisputably possesses the requisite mens rea for a federal crime involving the use of force
against, or causing the death of, another, the defendant is not guilty of the crime if he or she
subjectively believed the force used was necessary and that belief was objectively reasonable
under the circumstances.286 Additional defenses such as duress and necessity likewise do not
ordinarily “negate a defendant’s criminal state of mind” but allow “the defendant to avoid

281 See United States v. Bank of New England, N.A., 821 F.2d 844, 856 (1st Cir. 1984) (“[A] corporation cannot plead
innocence by asserting that the information obtained by several employees was not acquired by any one individual who
then would have comprehended its full import. Rather the corporation is considered to have acquired the collective
knowledge of its employees and is held responsible for their failure to act accordingly.” (quoting United States v.
T.I.M.E.–D.C., Inc., 381 F. Supp. 730, 738 (W.D. Va. 1974)).
282 E.g., United States v. Sci. Applications Int’l Corp., 626 F.3d 1257, 1275 (D.C. Cir. 2010). One commentator has
framed criticism of the collective knowledge doctrine as centering on the proposition that the doctrine creates an
“unrealistic requirement that senior management keep track of the knowledge of all of its employees.” Sheley, supra
note 280, at 783.
283 MODEL PENAL CODE § 2.07(1)(c) (1985). Liability extends more broadly to corporate agents for what the MPC
deems “violations,” which generally impose strict liability, among other things. Id. §§ 2.05, 2.07(1)(a).
284 E.g., Mihailis E. Diamantis, Corporate Criminal Minds, 91 NOTRE DAME L. REV. 2049, 2068 (2016). Professor
Diamantis notes, for instance, that those at the top of the corporate hierarchy generally are “uninformed about and
uninvolved in the day-to-day activities of a corporation, where criminal action often takes place[.]” Id. at 2068-69.
285 United States v. Toledo, 739 F.3d 562, 567 (10th Cir. 2014).
286 Id. at 568 (“Self-defense only requires the defendant's reasonable belief that deadly force was necessary, not that he
exercise a duty to retreat or recognize the unavailability of reasonable alternatives.”); United States v. Earth, 984 F.3d
1289, 1300 (8th Cir. 2021) (approving jury instructions stating that if “a person reasonably believes force is necessary
to protect herself from what she reasonably believes to be unlawful physical harm about to be inflicted by another and
uses that force, then she acted in self-defense”); United States v. Biggs, 441 F.3d 1069, 1071 (9th Cir. 2006) (requiring
“a reasonable belief that the use of force was necessary to defend himself or another against the immediate use of
unlawful force”). In the context where self-defense often arises—a federal prosecution for homicide under particular
jurisdictional circumstances—an unreasonable but honest belief that the force used was necessary, amounting to
criminal negligence, may constitute “imperfect self-defense” that permits conviction of involuntary manslaughter rather
than, say, second-degree murder. Toledo, 739 F.3d at 568; United States v. Milk, 447 F.3d 593, 599 (8th Cir. 2006).
The MPC approach makes the defense unavailable where the defendant’s belief as to the unlawfulness of the conduct
being used against him is erroneous due to ignorance or a mistake regarding the law. MODEL PENAL CODE § 3.09
(1985).
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liability”287 based on conditions that justify the criminal conduct and involve proof (among other
things) of certain objectively reasonable beliefs on the defendant’s part.288 Statutory defenses
established by Congress and applicable only to specific federal offenses may also necessitate
proof of some mental state independent of the mens rea required for commission of the crime. For
example, 18 U.S.C. § 2243(a) prohibits, in certain jurisdictional contexts, knowingly engaging in
a sexual act with another person who is between 12 and 15 years old when there is at least a four-
year age difference between the two people.289 The mens rea required for commission of the
crime is knowingly engaging in the sexual act; the defendant need not have known the age of the
victim or the age difference.290 However, the statute provides a defense if “the defendant
reasonably believed that the other person had attained the age of 16 years.”291
Other defenses to federal criminal liability focus on circumstances that negate the defendant’s
mens rea with respect to the charged crime. Voluntary intoxication, for instance, is generally
recognized by the federal courts as a defense that may negate the mens rea of a specific-intent,
but not a general-intent, crime.292 A mistake may operate similarly.293 The federal insanity

287 Dixon v. United States, 548 U.S. 1, 7 (2006).
288 E.g., United States v. Nwoye, 824 F.3d 1129, 1136-37 (D.C. Cir. 2016) (recognizing that defendant must have had a
“reasonable fear” of imminent danger, among other things); United States v. Dixon, 901 F.3d 1170, 1176 (10th Cir.
2018) (requiring “well-grounded apprehension” of danger and direct causal relationship that could be “reasonably
anticipated” between criminal action and avoiding threatened harm ); United States v. Miller, 59 F.3d 417, 422 (3d Cir.
1995) (additionally requiring that defendant did not “recklessly place herself in a situation in which she would be
forced to engage in criminal conduct”); United States v. Dixon, 413 F.3d 520, (5th Cir. 2005), aff’d, 548 U.S. 1 (2006)
(defendant must not have “recklessly or negligently placed herself in a situation in which it was probable” she would be
forced to commit crime).
289 18 U.S.C. § 2243(a).
290 Id. § 2243(d) (providing that the government “need not prove that the defendant knew” age or requisite age
difference); United States v. White Calf, 634 F.3d 453, 457 (8th Cir. 2011) (“§ 2243(d) makes clear that the
government’s burden to prove scienter in a § 2243(a) prosecution is limited to proving the defendant knowingly
engaged in a sexual act.” (alteration and internal quotation marks omitted)).
291 Id. § 2243(c)(1). It is also a defense under the statute that, at the time of the sexual act, the persons engaging in it
were married to each other. Id. § 2243(c)(2).
292 E.g., United States v. Garrett, 898 F.3d 811, 814 (8th Cir. 2018) (“It is widely accepted by this court and others that
a defendant charged with a specific intent crime is entitled to an intoxication instruction when the evidence would
support a finding that the defendant was in fact intoxicated and that as a result there was a reasonable doubt that he
lacked specific intent.” (alterations and internal quotation marks omitted)); Faucett v. United States, 872 F.3d 506, 510
(7th Cir. 2017) (“[W]e have on a few occasions dealt with a claim of voluntary intoxication; each time we’ve treated it
as a ‘negative’ defense to a specific-intent crime that negates the mens rea of the crime.” (alteration omitted)); United
States v. Lamott, 831 F.3d 1153, 1156 (9th Cir. 2016) (acknowledging concession “that voluntary intoxication is a
defense to specific intent crimes, but not to general intent crimes”); United States v. Dyke, 718 F.3d 1282, 1293 (10th
Cir. 2013) (“Voluntary intoxication can be used, of course, as a mens rea defense to specific intent crimes[.]”). Given
the lack of clarity as to the meaning of general intent and specific intent, as described elsewhere in this report, the
limitation to specific-intent crimes “has generated substantial litigation” as to whether particular federal criminal
statutes require one or the other (and thus may be subject to an intoxication defense). Garrett, 898 F.3d at 814 n.3. The
MPC appears to strictly limit when intoxication may serve as a defense while acknowledging that it may so serve if “it
negatives an element of the offense,” though lack of awareness of a risk, due to self-induced intoxication, of which the
defendant would otherwise be aware is excepted when recklessness is the requisite culpability element. MODEL PENAL
CODE § 2.08 (1985).
293 See Rehaif v. United States, 139 S. Ct. 2191, 2198 (2019) (recognizing that “mistaken impression” as to a collateral
legal matter can result in defendant “not hav[ing] the guilty state of mind that the statute’s language and purposes
require”); United States v. Vasarajs, 908 F.2d 443, 447 n.7 (9th Cir. 1990) (“Generally, a criminal defendant’s mistake
of fact can only be a valid defense if it negates the existence of a requisite mens rea component of the crime charged
and if the crime allows for the interposition of such a defense.”); United States v. Miranda-Enriquez, 842 F.2d 1211,
1213 (10th Cir. 1988) (“[A] mistake defense is possible only if there is some mental state required to establish a
material element of the crime that the mistake can negate.” (quoting United States v. Anton, 683 F.2d 1011, 1013 (7th
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defense, codified at 18 U.S.C. § 17, recognizes a defense for persons with conditions that may
negate the requisite mens rea and conditions that have been deemed independently to justify
declining to impose criminal liability. The statute provides an affirmative defense if a “severe
mental disease or defect” leaves the defendant “unable to appreciate” either (1) the “nature and
quality” of his acts or (2) “the wrongfulness” of his acts.294 The first prong, referred to by the
Supreme Court as the “cognitive capacity” prong, involves an inquiry into “whether a mentally ill
defendant could comprehend what he was doing when he committed a crime,” for if he “had no
such capacity, he could not form the requisite intent—and thus is not criminally responsible.”295
The second prong, “moral capacity,” looks to whether the defendant, regardless of his awareness
of the nature of his conduct or intent to do the proscribed act or bring about the proscribed result,
could “distinguish right from wrong when committing his crime.”296 At least one circuit has
concluded that “wrongfulness for purposes of the federal insanity defense statute is defined by
reference to objective societal or public standards of moral wrongfulness, not the defendant’s
subjective personal standards of moral wrongfulness.”297 Thus, under this conception, what the
defendant would personally believe to be right and wrong is irrelevant.
Federal Mens Rea Reform and Considerations for
Congress
After the efforts of the congressionally created National Commission on Reform of Federal
Criminal Laws did not yield significant changes to federal mens rea requirements in the 1970s,298
some commentators continued to urge reforms consistent with, or building on, the MPC
approach.299 In 2013, the House Judiciary Committee established a “bipartisan task force on over-
criminalization” to review “current federal criminal statutes and make recommendations for
improvements.”300 One of the issues the task force reviewed was “the lack of a consistent and

Cir. 1982) (internal quotation marks omitted)). The MPC makes clear that a mistake of fact or law is a defense if it
“negatives” the mental state “required to establish a material element of the offense,” among other things and with
some caveats. MODEL PENAL CODE § 2.04 (1985).
294 18 U.S.C. § 17(a).
295 Kahler v. Kansas, 140 S. Ct. 1021, 1026 (2020); see id. at 1038 (Breyer, J., dissenting) (noting that the “prong
corresponds roughly to the modern concept of mens rea for many offenses”). The Kahler Court was describing the two
prongs of the M'Naghten test, the “most famous statement of the traditional insanity defense” from a nineteenth-century
English case, id. at 1038 (Breyer, J., dissenting), but as the Court noted, the federal insanity-defense statute essentially
adopts that test. Id. at , 1037 (majority op.) (recognizing that “Congress chose in the end to adhere to the M'Naghten
rule”).
296 Id. at 1025, 1027.
297 United States v. Ewing, 494 F.3d 607, 621 (7th Cir. 2007); see also United States v. Cuebas, 415 F. App’x 390, 398
(3d Cir. 2011) (agreeing, in an unpublished opinion, with Ewing that “subjective moral justification plays no role in
determining whether a defendant was insane”).
298 LAFAVE, supra note 6, § 1.1(b). The Commission proposed generally applicable culpability rules and definitions
similar to those reflected in the MPC, which became the basis for several bills introduced in Congress in subsequent
years. E.g., Criminal Code Revision Act of 1983, H.R. 2013, 98th Cong. (1983).
299 E.g., Moohr, supra note 13, at 703-07 (noting default rule based on MPC that introductory mens rea term should
apply to each subsequent element had “benefit” of reducing inconsistent court decisions by “imposing a single
standard”).
300 Press Release, Congressman Bobby Scott, House Judiciary Committee Creates Bipartisan Task Force on Over-
Criminalization (Mar. 4, 2021), https://bobbyscott.house.gov/media-center/press-releases/house-judiciary-committee-
creates-bipartisan-task-force-on-over.
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adequate mens rea requirement in the federal code.”301 Relying on the work of the task force, “a
Criminal Justice Reform Initiative at the Judiciary Committee” was created in early 2015 “to
address the significant Congressional interest in criminal justice reform from Members who do
and do not serve on the Judiciary Committee.”302 Several bills stemming from this and other
legislative efforts303 in the 114th and 115th Congresses sought to make changes to the status quo
with respect to federal mens rea requirements. Though the proposals varied in the details, they
typically incorporated ideas and concepts stemming from the MPC approach to culpability.
Ultimately, none of the bills from prior Congresses became law. However, consideration of
altering federal mens rea requirements continues in the 117th Congress. On March 11, 2021,
several Senators introduced the Mens Rea Reform Act of 2021,304 multiple versions of which had
been introduced in earlier Congresses. This section describes the pending bill in the current
Congress, provides an overview of earlier legislation from the 114th and 115th Congresses305 that
would have impacted federal mens rea requirements, and briefly sets out some considerations for
Congress reflected in these legislative efforts.
117th Congress
The Mens Rea Reform Act of 2021 would establish that for elements of most federal criminal
offenses “for which the text . . . does not specify a state of mind,” a default mens rea of
“willfully” would apply.306 The bill would define “willfully” as knowledge of unlawfulness and,
for elements involving the nature, circumstances, object, or result of conduct of a person, that the
person knew of and had as his or her conscious object the accomplishment of conduct of that
nature, with those circumstances, or with the object or result.307 In other words, the bill sets as a
default mens rea standard that one act purposely and with knowledge that one’s conduct is
unlawful. The bill also provides that where a mens rea term is present but the text of the offense
does not specify the elements to which it applies, the term applies to all elements unless “a
contrary purpose plainly appears.”308 Exception is made to both the default mens rea term and
default application rules if (1) the text makes clear that no state of mind was meant to be required
for such element, (2) the element establishes jurisdiction or venue, or (3) applying either rule
would “lessen the degree of mental culpability” for that element under Supreme Court precedent

301 REP. BOBBY SCOTT, H. COMM. ON THE JUDICIARY, 113TH CONG., DEMOCRATIC VIEWS ON CRIMINAL JUSTICE REFORMS
RAISED BEFORE THE OVER-CRIMINALIZATION TASK FORCE & THE SUBCOMMITTEE ON CRIME, TERRORISM, HOMELAND
SECURITY, AND INVESTIGATIONS 99 (2013), https://www.nacdl.org/getattachment/b88e9bed-f28b-441b-99a6-
cfcb4745fa4b/overcriminalization-task-force-democrats-report.pdf.
302 H.R. Rep. No. 114-889, at 2 (2016).
303 E.g., The Adequacy of Criminal Intent Standards in Federal Prosecutions: Hearings Before the Senate Judiciary
Committee, 114th Cong. (2016).
304 Mens Rea Reform Act of 2021, S. 739, 117th Cong. (2021).
305 Though it does not appear that legislation was introduced in the 116th Congress that would have made wholesale
changes to federal mens rea requirements, bills introduced in the House and Senate would have taken a preliminary,
information-gathering step of requiring the Attorney General and agency heads to compile into a report all federal
statutory and regulatory criminal offenses and list for each, among other things, the applicable mens rea requirement.
See Next Step Act of 2019, H.R. 1893 & S. 697, 116th Cong. § 305(b)-(c) (2019). At least one bill in the 117th
Congress would do the same. See Smarter Sentencing Act of 2021, S.1013, 117th Cong. § 5 (2021).
306 S. 739, 117th Cong. § 2(a) (2021). The bill would exclude offenses that are not punishable by imprisonment or a
maximum criminal fine of at least $2,500, as well as military offenses governed by Title 10 and state laws adopted for
certain areas within federal jurisdiction. Id.
307 Id.
308 Id.
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or existing statutory or regulatory law.309 With respect to the exception for textual clarity that no
state of mind is required, the bill would specify that “the mere absence of a specified state of
mind for an element of a covered offense in the text of the covered offense shall not be construed
to mean that Congress affirmatively intended not to require the Government to prove any state of
mind with respect to that element.”310 Put differently, for Congress to provide for strict liability
for an element of a federal offense, it would need to explicitly denote in the text of the offense
that no mens rea is required for that element. The bill would expressly apply to existing
offenses,311 meaning that some federal offenses silent as to mens rea that had previously been
interpreted as strict liability could now carry a heightened state-of-mind requirement, were the
bill to become law.312
114th and 115th Congresses
An earlier version of the bill from the 117th Congress was first introduced in the 114th Congress.
The Mens Rea Reform Act of 2015313 would have required (with some exceptions) that with
respect to any element for which the text of an offense “does not specify a state of mind,” the
government must prove that the defendant acted willfully.314 The bill also would have established
a default distribution rule when application of a term is unclear. Specifically, where a covered
offense specifies the requisite mens rea but does not specify to which elements of the offense the
requirement applies, the bill would have required that the requisite mens rea “apply to all
elements of the covered offense” subject to exceptions including a plain contrary purpose in the
statute and jurisdictional elements, among other things.315 The version of the Mens Rea Reform
Act from the 114th Congress would have provided definitions for certain mens rea terms as well,
defining the term “knowingly” as awareness with respect to conduct and circumstance elements
and awareness that conduct is practically certain to cause a result with respect to result elements,
in a manner largely consistent with the MPC’s approach.316 The bill also would have defined
“willfully” for purposes of the default mens rea requirement as “knowledge that the person’s
conduct was unlawful.”317
Another bill from the 114th Congress, The Stopping Over-Criminalization Act of 2015, H.R.
3401, would have imposed a default mens rea requirement of knowledge in the absence of
specification otherwise “in the provision of law defining the offense,” though offenses “where a
defendant might reasonably be unaware the conduct could be criminally punished” would have

309 Id.
310 Id.
311 The bill would also apply to some offenses that occurred prior to enactment, with a number of exceptions (for
example, if applying the new legislation would punish as a crime conduct that was innocent when done). Id.
312 Recent arguments in support of and opposition to altering federal mens rea requirements appear to fall along similar
lines as the positions taken regarding previous legislative efforts, described infra. For an elaboration of these
arguments, see generally Benjamin Levin, Mens Rea Reform and its Discontents, 109 J. CRIM. L. & CRIMINOLOGY 491
(2019).
313 As described supra and infra, modified versions of the Mens Rea Reform Act were reintroduced in the 115th and
117th Congresses. Mens Rea Reform Act of 2017, S. 1902, 115th Cong. (2017); Mens Rea Reform Act of 2018, S.
3118, 115th Cong. (2018); Mens Rea Reform Act of 2021, S. 739, 117th Cong. (2021).
314 Mens Rea Reform Act of 2015, S. 2298, 114th Cong. § 2 (2015).
315 Id. § 2(c)-(d).
316 Id. § 2(a).
317 Id.
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required proof that “the defendant had reason to know the defendant’s conduct was unlawful.”318
The bill would have applied its default state of mind to “each element of the offense” with
exception only for specific provision otherwise in the law defining the offense.319 The Criminal
Code Improvement Act of 2015, also from the 114th Congress, would have established that if “no
state of mind is required by law” for a federal criminal offense, “the state of mind the government
must prove is knowing” unless the offense involves conduct that a reasonable person in the same
or similar circumstances would not know or have reason to know was unlawful, in which case
“the Government must prove that the defendant knew, or had reason to believe, the conduct was
unlawful.”320
The Criminal Code Improvement Act of 2015, H.R. 4002, was reported out of committee on
November 18, 2015.321 Proponents of the bill, and of mens rea reform more generally, urged that
the existing lack of clarity as to the requisite mental state for certain crimes violates principles of
fair notice and asserted that strict liability offenses or offenses with relatively minimal mental-
state requirements represent part of a larger, concerning trend of federal over-criminalization that
Congress should seek to remedy.322 Opposition to establishing mental-state requirements that
would apply across federal criminal law centered on the prospect that such requirements could
make it harder to punish corporate actors under provisions meant to protect public health and
welfare.323 Representatives of the Department of Justice noted the difficulties that applying newly
formulated broad-brush mental-state requirements could create in pursuing some significant
cases, suggesting that indiscriminate application of such rules to existing offenses could have
unintended consequences.324 Ultimately, neither the Criminal Code Improvement Act of 2015 nor
the other legislation discussed above from the 114th Congress became law.

318 Stopping Over-Criminalization Act of 2015, H.R. 3401, 114th Cong. § 3 (2015).
319 Id.
320 Criminal Code Improvement Act of 2015, H.R. 4002, 114th Cong. § 11 (as reported by H. Comm. on the Judiciary,
Dec. 23, 2016).
321 See Markup of H.R. 2830; H.R. 3713; H.R. 4002; H.R. 4003; H.R. 4001; H.R. 4023 Before the House Judiciary
Committee, 114th Cong. 53 (2015).
322 E.g., Sens. Chuck Grassley & Orrin Hatch, Mens Rea Reform and the Criminal Justice Reform Constellation,
WASH. EXAMINER (July 19, 2018), https://www.judiciary.senate.gov/press/rep/commentary/grassley-hatch-op-ed-mens-
rea-reform-and-the-criminal-justice-reform-constellation (arguing that when “crimes are drafted without clear criminal
intent requirements, it becomes increasingly easy for unsuspecting Americans to be sent to jail for conduct they had no
idea was against the law”); see also John Malcolm, The Pressing Need for Mens Rea Reform, THE HERITAGE
FOUNDATION (Sept. 1, 2015), http://www.heritage.org/research/reports/2015/09/the-pressing-need-for-mens-rea-reform.
323 See, e.g., Mike DeBonis, The Issue that Could Keep Congress from Passing Criminal Justice Reform, WASH. POST
(Jan. 20, 2016), https://www.washingtonpost.com/news/powerpost/wp/2016/01/20/the-issue-that-could-keep-congress-
from-passing-criminal-justice-reform/ (referencing view that applying willfulness requirement across federal criminal
law would constitute “a quiet attempt to make it ever more difficult for the federal government to prosecute
corporations and their executives for crimes against the public welfare”); Editorial Board, Don’t Change the Legal Rule
on Intent, N.Y. TIMES (Dec. 5, 2015), https://www.nytimes.com/2015/12/06/opinion/sunday/dont-change-the-legal-
rule-on-intent.html?_r=0.
324 E.g., DeBonis, supra note 323 (describing supposition of chief of DOJ Criminal Division that applying willfulness
requirement to offense of murdering a U.S. national abroad could make proving terrorist mental state “a difficult if not
impossible task”); Matt Apuzzo & Eric Lipton, Rare White House Accord with Koch Brothers on Sentencing Frays,
N.Y. TIMES (Nov. 24, 2015), https://www.nytimes.com/2015/11/25/us/politics/rare-alliance-of-libertarians-and-white-
house-on-sentencing-begins-to-fray.html (suggesting that application of knowledge-of-unlawfulness standard could
have prevented guilty pleas in cases involving food-borne illness and mislabeling of prescription medication).
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The Mens Rea Reform Act was reintroduced in the Senate in the 115th Congress with some
changes clarifying the definition of willfulness and the application of the requirement to existing
offenses, among other things, but that bill likewise did not become law.325
Considerations for Congress
The bills discussed above, which sought or seek to address in different ways recurrent issues with
respect to federal mens rea requirements, raise distinct interpretive questions that Congress might
examine. One question is how stringent a default mental-state requirement should be where the
statute is silent. As described previously, federal courts will ordinarily presume that a mens rea
element is included in a criminal offense even if it is not explicit in the text, and usually that
element is set at least at the level of knowledge.326 Two of the bills described above would appear
to have codified that default by making knowledge the statutory standard unless otherwise
provided, while the various versions of the Mens Rea Reform Act set out a higher default of
willfulness but with different definitions (i.e., knowledge of unlawfulness or, in the formulation
from the bill pending in the 117th Congress, purpose and knowledge of unlawfulness).327 All of
the aforementioned bills would have impacted the degree to which courts might recognize an
exception to the presumption of scienter in the case of certain kinds of public-welfare offenses for
which strict liability might ordinarily be deemed appropriate, as would the version of the Mens
Rea Reform Act pending in the 117th Congress. Even the two bills that would have established a
knowledge default for many kinds of offenses would appear to have disfavored the kinds of
regulatory and public-welfare offenses for which courts might recognize strict liability, as many
such offenses could be viewed as involving conduct that “a reasonable person . . . would not have
reason to believe[] was unlawful” or “criminally punished” and would thus have been subject to a
special rule requiring at least “reason to know” or “reason to believe” such conduct was, in fact,
unlawful.328
A related question raised by the bills from the 114th and 115th Congresses and the bill pending in
the 117th Congress is when a statute can be deemed silent on the question of mens rea such that a
statutory default would apply. For instance, the Criminal Code Improvement Act of 2015 would
have added a mental-state requirement to any federal criminal offense for which “no state of mind
is required by law,” but would not have made clear whether “required by law” would have been
limited to offenses that are textually silent as to mental state or would have included judicial
interpretations regarding an offense’s mens rea requirement.329 The bill likewise would have had

325 Mens Rea Reform Act of 2018, S. 3118, 115th Cong. (2018). An earlier version of the bill, introduced in 2017, was
identical to the legislation now pending in the 117th Congress. Compare Mens Rea Reform Act of 2017, S. 1902, 115th
Cong. (2017), with Mens Rea Reform Act of 2021, S. 739, 117th Cong. (2021).
326 See supra notes 100-104 and accompanying text.
327 Neither of the bills requiring knowledge as a default would have defined that mental state more precisely, meaning
that the term presumably would still have been subject to different definitions depending on the court. See supra notes
161-178 and accompanying text.
328 Criminal Code Improvement Act of 2015, H.R. 4002, 114th Cong. § 11 (as reported by H. Comm. on the Judiciary,
Dec. 23, 2016); Stopping Over-Criminalization Act of 2015, H.R. 3401, 114th Cong. § 3 (2015). The version of the
Mens Rea Reform Act introduced in 2018 also would have required federal agencies to revisit offenses found in
regulations and “specify[] the state of mind required for each element” of the offense (if not already clear), and strict-
liability elements in regulatory offenses would have been explicitly prohibited. S. 3118, 115th Cong. § 101(a) (2018).
329 See Orin Kerr, A Confusing Proposal to Reform the ‘Mens Rea’ of Federal Criminal Law, WASH. POST (Nov. 25,
2015), https://www.washingtonpost.com/news/volokh-conspiracy/wp/2015/11/25/a-confusing-proposal-to-reform-the-
mens-rea-of-federal-criminal-law/ (“Does ‘required by law’ mean ‘expressly written into the text,’ or does that mean
‘required by the statute as interpreted by judicial precedent’?”). The committee report referenced “longstanding
statutory law and established case-law” and stated that the bill’s intent was “not to require Federal courts to apply a
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uncertain application to an offense with a mental-state requirement textually or judicially
assigned to some, but not all, of its elements. The Mens Rea Reform Act of 2021 pending in the
117th Congress would address this issue by limiting its default mental-state requirement to “any
element of the offense for which the text of the covered offense does not specify a state of mind,”
but exceptions would be made if, among other things, the result would “lessen the degree of
mental culpability” required to be proven for a given element under other provisions of law or
Supreme Court precedent.330
One version of the Mens Rea Reform Act from the 115th Congress would have modified the
reach of its default requirement by providing that for existing offenses lacking a state-of-mind
requirement for one or more elements either in the text of the offense or under Supreme Court
precedent, a default mens rea of willfulness would apply in the absence of a contrary provision in
statutory text or an applicable exception.331 This provision potentially could have operated to
overrule Supreme Court precedent with respect to its interpretation of existing federal crimes that
lack a mental-state requirement for at least one element to the extent such precedent recognized a
lower, or no, mens rea for that or another element.
Another question raised by the bills is whether, how, and under what circumstances to apply a
distribution rule for a mens rea term whose application to certain elements of an offense is
unclear. Currently, a federal court assessing whether a particular element of an offense carries a
mens rea requirement will ask if it criminalizes otherwise innocent conduct, a statute-specific
inquiry that may be less than pellucid.332 The Mens Rea Reform Act of 2021 would eschew this
approach in favor of a clearer distribution rule akin to the MPC position—a mens rea requirement
in the text of a federal criminal offense would apply to each element of the offense unless an
exception applied.333 Earlier versions of the Mens Rea Reform Act would have operated
similarly,334 as would the Stopping Over-Criminalization Act of 2015.335 That latter bill would
have made exception only where “otherwise specifically provided in the provision in the law
defining the offense,”336 however, whereas the Mens Rea Reform Act of 2021 would make
exception for elements relating to jurisdiction and venue and, among others, circumstances where
the text of an offense makes clear that Congress “affirmatively intended” no mental-state
requirement to apply or where application of the default would actually lessen the requisite
mental state under Supreme Court precedent.337
As the above discussion reflects, even setting aside the prospect of more broadly systematizing
and codifying mental-state term definitions in federal law, efforts to establish general application

‘knowingly’ standard in areas where the caselaw is settled.” H.R. Rep. No. 114-889, at 4-5 (2016). Even with that
guidance, it would not have been clear what constitutes “settled” caselaw and whether that includes only Supreme
Court precedent or lower-court decisions as well. See Kerr, supra (“Let’s say that a statute has no express mental state,
but the Supreme Court has said that the required mental state is intent. Does this new provision trump the Supreme
Court, lowering the mental state back down to knowing? Or does the precedent still apply? If precedents still apply,
what if the precedents are lower court cases that have not been uniformly adopted? Would a court follow the precedent
where it is binding but not where it isn’t, leading to different interpretations of the law? And if that happened, what
standard of ‘required by law’ would the Supreme Court use to resolve the differences?”).
330 S. 739, 117th Cong. § 2(a) (2021).
331 S. 3118, 115th Cong. § 101(a) (2018).
332 See supra notes 133-149 and accompanying text.
333 S. 739, 117th Cong. § 2(a) (2021).
334 E.g., S. 2298, 114th Cong. § 2(a) (2015).
335 See H.R. 3401, 114th Cong. § 3 (2015).
336 Id.
337 S. 739, 117th Cong. § 2(a) (2021).
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Mens Rea: An Overview of State-of-Mind Requirements for Federal Criminal Offenses

rules or default requirements in the absence of clear legislative drafting can raise a host of
questions that Congress might examine in the 117th Congress in relation to the Mens Rea Reform
Act of 2021 or any other legislation addressing the topic that might be introduced. As of this
writing, no action has been taken on the Mens Rea Reform Act of 2021.

Author Information

Michael A. Foster

Legislative Attorney

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