The International Court of Justice and the International Criminal Court: A Primer

The International Court of Justice and the International Criminal Court: A Primer

The International Court of Justice and the
April 4, 2024
International Criminal Court: A Primer
Karen Sokol
International courts are distinctive types of international institutions. They are created by nation-
Legislative Attorney
states, either directly or through international organizations, to resolve disputes and to advance

the development of international law through judicial decisionmaking. Two international
courts—the International Court of Justice (ICJ) and the International Criminal Court (ICC)—

have been particularly prominent on the global stage and have garnered considerable interest
from Members of Congress.
The structure of each court and its jurisdictional authorities are specified in the court’s respective originating treaty. The ICJ
was established by the U.N. Charter in 1945 as part of the United Nations, and the ICC was established almost five decades
later in a treaty called the Rome Statute. The ICJ’s mandate is to resolve interstate disputes about questions of international
law that the states that are parties to a case have consented to the court’s jurisdiction to address, and to answer certain
questions of international law that U.N. bodies periodically ask the court to address. States may consent to the ICJ’s
jurisdiction—and thus to be bound by its decisions—by submitting an instrument of acceptance with the court, becoming a
party to a treaty that includes a provision allowing parties to submit disputes about the treaty to the ICJ, or by agreeing with
another state or states to submit a particular dispute to the ICJ.
The ICC’s mandate, on the other hand, is to prosecute individuals on charges of one or more of four international crimes,
which are considered to be of the most serious concern to the entire international community: genocide, crimes against
humanity, war crimes, and aggression. The ICC’s jurisdiction to investigate and prosecute depends on a combination of
factors, including the nationality of the alleged offender, the location of the alleged crime, and the way in which the case is
initiated. The court may exercise jurisdiction over crimes committed by the nationals of or on the territory of Rome Statute
states parties or of states that have accepted the court’s jurisdiction for that purpose. The ICC’s authority to investigate and
prosecute individuals for alleged commission of one or more of the four Rome Statute crimes may be triggered through a
referral either by a state party or by the U.N. Security Council or through initiation by the ICC Prosecutor.
In contrast to domestic legal systems, there are no centralized mechanisms for enforcing the decisions of international courts
such as the ICJ and the ICC. Rather, international courts are dependent on the states that created them—individually and
collectively—to comply with, support, and enforce their decisions.
The U.S. relationship with the ICJ and the ICC over the course of each court’s existence has been varied and often complex,
and Congress has always played an important role in this relationship. When then-President Truman submitted the U.N.
Charter to the Senate in 1945, the Senate approved the U.S. status as a party to the ICJ by providing its advice and consent.
Congress restricted the President’s ability to ratify the Rome Statute, on the other hand, by passing legislation prohibiting the
United States from becoming a party to the ICC without Senate advice and consent. Congress also impacts the courts’ work
by passing legislation that authorizes and constrains the executive branch—both directly and through appropriations—in its
interactions with the courts. Further, Congress makes periodical recommendations regarding the courts, including, for
example, urging the Administration to bring a case before the ICJ and urging the international community to adhere to an ICJ
decision.

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Contents
Creation ........................................................................................................................................... 1
The ICJ: The U.N. Charter, 1945 .............................................................................................. 1
The ICC: The Rome Statute, 2002 ............................................................................................ 2
Structure .......................................................................................................................................... 5
The ICJ ...................................................................................................................................... 5
The ICC ..................................................................................................................................... 6
Jurisdiction ...................................................................................................................................... 6
The ICJ’s Case Jurisdiction ....................................................................................................... 7
Contentious Jurisdiction...................................................................................................... 8
Advisory Jurisdiction ......................................................................................................... 11
The ICC ................................................................................................................................... 12
Case Initiation by State Party Referral or by the ICC Prosecutor ..................................... 12
Case Initiation by Security Council Referral .................................................................... 13
The ICC Jurisdiction in Practice: Investigation of Crimes Committed in Ukraine .......... 15
Effect of Decisions & Enforcement Mechanisms ......................................................................... 15
The ICJ .................................................................................................................................... 15
Contentious Cases ............................................................................................................. 15
Advisory Opinions ............................................................................................................ 17
The ICC ................................................................................................................................... 17
Conclusion ..................................................................................................................................... 17

Contacts
Author Information ........................................................................................................................ 18

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The International Court of Justice and the International Criminal Court

n recent years, cases before the International Court of Justice (ICJ) and investigations by the
International Criminal Court (ICC) have sparked widespread global interest,1 including on the
I part of Congress.2 To support Congress’s consideration of how these courts operate and their
impacts on the United States and the broader international community, this report explains (1)
how and why states3 created each court, (2) the courts’ structures, (3) the bases on which they are
authorized to exercise jurisdiction, and (4) the effects of their decisions and potential mechanisms
for enforcement. Each of these discussions highlights the key differences between the two courts
and the interaction of the United States with them over time. This report concludes by discussing
the relevance of this information for Congress as it observes how the ICJ and ICC carry out the
mandates that states established them to fulfill.
Creation
The ICJ and the ICC are both international tribunals created by states through treaties. Each
tribunal’s originating treaty sets out the court’s structure and authorities. The ICJ is the older of
the two courts, predating the ICC by half a century. Although the two courts are distinctive in
important ways, they were both created for the general purpose of contributing to peace and
security by providing a legal mechanism to resolve problems and by promoting the development
of international law through judicial decisionmaking.4
The ICJ: The U.N. Charter, 1945
The ICJ is a permanent international court created in 1945 by the U.N. Charter as the “principal
judicial organ” of the United Nations.5 States parties established the ICJ to, first and foremost,
provide them with a judicial method for the pacific settlement of international disputes

1 See, e.g., Mike Corder, 5 European Nations and Canada Seek to Join Genocide Case Against Myanmar at Top UN
Court, AP NEWS (Nov. 16, 2023, 2:31 PM), https://apnews.com/article/myanmar-rohingya-britain-gambia-genocide-
0ec2ce873669c8ada585e10dde91d284; Michael Rios, Five Countries Ask International Criminal Court to Investigate
the Situation in Palestinian Territories, CNN (Nov. 17, 2023, 6:18 PM),
https://www.cnn.com/2023/11/17/middleeast/israel-gaza-war-crimes-icc-referral/index.html; UN Court Gets Request
for Advisory Opinion on Climate Change, U.S. NEWS (Apr. 19, 2023, 2:24 PM),
https://www.usnews.com/news/us/articles/2023-04-19/un-court-gets-request-for-advisory-opinion-on-climate-change.
2 See, e.g., Press Release, Senator Chris Coons, U.S. Senate, Senators Coons and Portman Statement on Congressional
Delegation to The Hague (Nov. 5, 2022), https://www.coons.senate.gov/news/press-releases/senators-coons-and-
portman-statement-on-congressional-delegation-to-the-hague; Press Release, Rep. Kathy Manning & Rep. Chris Smith,
U.S. House of Reps., Manning, Smith Lead 210 Members in Bipartisan Letter Denouncing South Africa’s Claims
Against Israel at International Court of Justice (Jan. 23, 2024), https://manning.house.gov/media/press-
releases/manning-smith-lead-210-members-bipartisan-letter-denouncing-south-africas.
3 At the international level, countries are typically referred to as “states.” See, e.g., U.N. Charter art. 2, ¶ 4 (requiring all
members of the United Nations to “refrain in their international relations from the threat or use of force against the
territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the
United Nations”). This Report follows that convention.
4 See generally Mary Ellen O’Connell & Lenore VanderZee, The History of International Adjudication, in THE OXFORD
HANDBOOK OF INTERNATIONAL ADJUDICATION 41 (Cesare P.R. Romano et al., eds., 2014) (discussing the development
of international courts as a means of providing an alternative to conflict and accountability for unlawful conduct
considered to threaten international peace and security); see also ELBERT THOMAS, INTERNATIONAL COURT OF JUSTICE:
REPORT TO ACCOMPANY S. RES. 196, S. Rep. No. 79-1835, at 3 (1946) (“[G]eneral worldwide acceptance of the
jurisdiction of the International Court of Justice in legal cases . . . would, in a substantial sense, place international
relations on a legal basis, in contrast to the present situation, in which states may be their own judge of the law.”).
5 U.N. Charter art. 92.
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(alongside, for example, diplomacy, negotiations, mediation, and arbitration).6 Because the ICJ is
a permanent court,7 it is able to produce a body of caselaw that contributes to the clarification and
development of international law over time.8
The ICJ’s functions are governed by the Statute of the International Court of Justice (ICJ
Statute)—an annex to and “an integral part of the [U.N.] Charter.”9 The ICJ was modeled on the
Permanent Court of International Justice (PCIJ),10 which states established at the end of World
War I in the Covenant of the League of Nations.11 During World War II, the United States played
a central role in advocating both for the establishment of a new international court to replace the
PCIJ and in developing the court’s structure and mandates.12 The ICJ began its work in 1946.
Although the PCIJ dissolved that same year, its decisions continue to be of persuasive value.13
Like all members of the United Nations, the United States is a party to the ICJ Statute.14
The ICC: The Rome Statute, 2002
More than half a century after the ICJ was established, the ICC began its work after its originating
treaty—the Rome Statute of the International Criminal Court (Rome Statute)—entered into force
in 2002.15 Unlike the ICJ, the ICC is not a part of the United Nations. The ICC does, however,
have a relationship with the United Nations in several respects. The U.N. Security Council may
both refer a case to the ICC16 and direct the ICC to defer an investigation for up to a year.17 The
ICC and the United Nations may also cooperate in various ways provided for in an agreement
between them.18
Unlike the ICJ, the ICC is a criminal court authorized to try individuals for certain serious crimes
rather than a court of general jurisdiction authorized to resolve legal disputes between states.
Before establishing the ICC, states had created a number of ad hoc tribunals to try individuals for

6 See History, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/history (last visited Apr. 1, 2024) [hereinafter
ICJ History].
7 See Statute of the International Court of Justice art. 23, ¶ 1.
8 See ICJ History, supra note 6. The decisions of arbitration panels and ad hoc courts are often cited and thus also can
support the development and clarification of international law, but they are more limited in this regard because they are
temporary institutions created solely to resolve a particular dispute or hear a specific set of cases. Consequently, these
bodies do not have the ability to develop a body of caselaw over time in the way permanent courts do. It was in part
because of this capacity that the United States and other countries justified their advocacy for the establishment of a
permanent international court after World War II. See ICJ History, supra note 6; infra text accompanying notes 11−12.
9 U.N. Charter art. 92.
10 See id.; see also Grant Gilmore, The International Court of Justice, 55 YALE L.J. 1049, 1049 (1946) (stating that the
ICJ “has replaced the League of Nations’ Permanent Court of International Justice with little change in the Court’s
constitution . . . , in the extent of its jurisdiction, or in the procedure prescribed under its Statute”).
11 See ICJ History, supra note 6. The Covenant of the League of Nations was part of the Treaty of Versailles and other
peace treaties signed in Paris after World War I. See United Nations Office at Geneva, The Covenant of the League of
Nations, https://www.ungeneva.org/en/about/league-of-nations/covenant (last visited Apr. 1, 2024).
12 See ICJ History, supra note 6.
13 Permanent Court of International Justice, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/pcij (last
visited Apr. 1, 2024).
14 See U.N. Charter art. 93, ¶ 1.
15 Rome Statute of the International Criminal Court (Rome Statute), July 17, 1998, 2187 U.N.T.S. 90.
16 See id., art. 13. The triggering of ICC jurisdiction by the Security Council is discussed further infra, “Case Initiation
by Security Council Referral.”
17 See Rome Statute, supra note 15, art. 16; infra “Case Initiation by Security Council Referral.”
18 See Rome Statute, supra note 15, art. 2; Relationship Agreement Between the United Nations and the International
Criminal Court, Oct. 4, 2004, 2283 U.N.T.S. 195.
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serious international crimes committed in various conflicts, including the Nuremberg and Tokyo
war crimes trials after World War II and, more recently, the International Criminal Tribunals for
Yugoslavia and Rwanda.19 Recognizing the utility of having a permanent international criminal
court available to investigate and prosecute “the most serious crimes of concern to the
international community as a whole,” however, states parties “establish[ed] an independent
permanent International Criminal Court . . . with jurisdiction over” crimes of such gravity that
they “threaten the peace, security and well-being of the world.”20
As discussed below, the Rome Statute recognizes four such crimes: genocide, crimes against
humanity, war crimes, and the crime of aggression.21 The ICC is not designed to replace national
jurisdiction but rather to “be complementary to” it.22 This principle of complementarity prevents
the ICC from investigating or prosecuting accused individuals when a national judiciary system is
already effectively doing so,23 thus making the ICC a forum “of last resort.”24
The United States is not a party to the Rome Statute.25 The United States did, however, actively
participate in the negotiations on the treaty, and the Clinton Administration signed it in December
2000.26 Before the negotiations, the Senate supported the creation of an international criminal
court, expressing its sense that such a court “would greatly strengthen the international rule of
law” and “thereby serve the interest of the United States and the world community.”27
This support was not unconditional. The Senate indicated that it would not support ratification of
a treaty allowing “representatives of any terrorist organization, including but not limited to the
Palestine Liberation Organization” or nationals of states supporting international terrorism to “sit
in judgement [sic] of American citizens.”28 The Senate also indicated its support for ratification of
a treaty creating an international criminal court was contingent upon U.S. “citizens [being]
guaranteed . . . that the court will take no action infringing upon or diminishing their rights under
the First and Fourth Amendments of the Constitution of the United States.”29
The Rome Statute was made open for signature in 1998, and shortly thereafter Congress passed
legislation prohibiting the United States from “becom[ing] a party to the International Criminal
Court except pursuant to a treaty under Article II of . . . the Constitution” and prohibiting the use

19 See Ad Hoc Tribunals, INT’L COMM. OF THE RED CROSS (Oct. 29, 2010), https://www.icrc.org/en/document/ad-hoc-
tribunals.
20 Rome Statute, supra note 15, pmbl.
21 See id. arts. 5−8 bis; infra “Jurisdiction” / “The ICC.”
22 Rome Statute, supra note 15, art. 1.
23 The Rome Statute requires the ICC to deem a case inadmissible whenever it “is being investigated or prosecuted by a
State which has jurisdiction over it, unless the State is unwilling or unable genuinely to carry out the investigation or
prosecution.” Id. art. 17, ¶ 1(a). Other aspects of the ICC’s jurisdiction are discussed further infra “Jurisdiction” / “The
ICC.”
24 Sang-Hyun Song, The Role of the International Court in Ending Impunity and Establishing the Rule of Law, U.N.
(December 2012), https://www.un.org/en/chronicle/article/role-international-criminal-court-ending-impunity-and-
establishing-rule-law.
25 See The States Parties to the Rome Statute, INTERNATIONAL CRIMINAL COURT, https://asp.icc-cpi.int/states-parties
(last visited Feb. 23, 2024) [hereinafter States Parties to the Rome Statute].
26 Press Release, President Bill Clinton, Statement on Signature of the International Criminal Treaty (Dec. 31, 2000),
https://1997-2001.state.gov/global/swci/001231_clinton_icc.html [hereinafter Clinton ICC Signing Statement].
27 Foreign Relations Authorization Act, Fiscal Years 1994 and 1995, Pub. L. 103-236, § 517(b)(1)-(2), 108 Stat. 382,
468-70 (1994). The Senate also called on the administration to “make every effort to advance” the proposed court. Id.§
517(b)(3).
28 Id. § 518.
29 Id. § 519.
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of funds to support the court unless the United States becomes a party through a treaty.30 When
President Clinton signed the Rome Statute in 2000, he acknowledged that it lacked binding legal
force upon the United States until it was ratified with Senate approval, and he further stated that
he would not submit the treaty for Senate approval immediately because “[t]he United States
should have the chance to observe and assess the functioning of the Court” before doing so.31
More specifically, Clinton expressed concern in large part about the possibility of ICC
prosecutions of U.S. nationals.32 For this reason, the United States attempted to persuade other
states that the Security Council—in which the United States has veto power as a permanent
member—should have greater control over referral of cases to the ICC than the Rome Statute
ultimately provided.33 Similar concerns led Congress to pass and President George W. Bush to
sign the American Servicemembers Protection Act of 2002 (ASPA),34 which provides for
measures to prevent the ICC from exercising jurisdiction over U.S. armed forces members,
officials, and government personnel;35 bars U.S. service members from participating in U.N.
peacekeeping operations that could put them in jeopardy of ICC prosecution;36 and prohibits
multiple types of U.S. assistance to and interactions with the court.37
ASPA does not preclude all U.S. engagement with the ICC: It does not “prohibit the United States
from rendering assistance to international efforts to bring to justice . . . foreign nationals accused
of genocide, war crimes or crimes against humanity.”38 Further, ASPA authorizes the President to
waive the statute’s prohibitions conditioned upon the Administration entering into an agreement
that would prohibit the ICC from exercising jurisdiction over U.S. armed forces members,
officials, and government personnel.39 After Russia’s 2022 invasion of Ukraine, Congress
amended ASPA to provide the executive branch with more authority to provide support to the ICC
in certain circumstances—specifically, “to assist with investigations and prosecutions of foreign
nationals related to the Situation in Ukraine, including to support victims and witnesses.”40
Since the ICC was established, the U.S. stance toward the court has shifted with administrations.
In 2002, President George W. Bush formally announced that the United States neither intended to
become a party nor recognized any legal obligations arising from the United States’ signature of
the Rome Statute.41 During the Obama Administration, the United States began participating in
the Rome Statute parties’ meetings as a non-state party observer.42 The Trump Administration

30 See Admiral James W. Nance and Meg Donovan Foreign Relations Authorization Act, Fiscal Years 2000 and 2001,
Pub. L. No. 106-113, § 705(a)-(b)), 113 Stat. 1501, 1501A-460 (1999) (codified at 22 U.S.C § 7401(a)-(b)).
31 Clinton ICC Signing Statement, supra note 26.
32 See id.; David J. Scheffer, The United States and the International Criminal Court, 93 AM. J. INT’L L. 12, 18 (1999).
33 See Scheffer, supra note 32, at 19–20. The authority of the Security Council to refer cases to the court and the United
States’ and other permanent Security Council members’ veto power is discussed infra, “Case Initiation by Security
Council Referral.”
34 Pub. L. No. 107-206, 116 Stat. 899 (codified at 22 U.S.C. §§ 7421-33).
35 See 22 U.S.C. § 7427(a)-(c).
36 See id. § 7424(b)-(c).
37 See id. §§ 7423–25.
38 Id. § 7433(a) (emphasis added).
39 Id. § 7422.
40 Department of State, Foreign Operations, and Related Programs Appropriations Act, 2023, Pub. L. No. 117-328,
§ 7073, 136 Stat. 5092 (2022) (codified at 22 U.S.C. § 7433(a)).
41 Letter from the United States to the Secretary-General, U.N. (May 6, 2002) (on file with U.N., Ref.
C.N.434.2002.TREATIES-21).
42 See Harold Hongju Koh, Legal Adviser, Dep’t of State, Address at the Annual Meeting of the American Society of
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subsequently expressed strong disapproval of the ICC’s investigation of whether U.S. military
and intelligence personnel committed war crimes in Afghanistan, issuing an executive order in
2020 that declared a national emergency and authorized sanctions against certain ICC officials
involved in the investigation.43 The Biden Administration rescinded that executive order in 202144
and again began participating as a non-party observer in the meetings of the ICC states parties.45
Structure
Each court’s respective originating treaty sets out the court’s structure and specifies how it is
governed by the states parties to the treaty.
The ICJ
Fifteen judges sit on the ICJ.46 They are elected by the U.N. member states for nine-year terms47
in parallel votes held in the Security Council and the General Assembly,48 from a list of persons
nominated by the national groups in the Permanent Court of Arbitration or national groups
appointed by governments that are not party to that body.49 Non-U.N. member states may also
nominate candidates pursuant to rules established by the General Assembly or by special
agreement.50 The ICJ Statute provides that the judges are to be “independent,” “of high moral
character,” and have “the qualifications required in their respective countries for appointment to
the highest judicial offices” or “recognized competence in international law.”51 In cases in which
one or more parties to a dispute do not have a judge of their same nationality on the bench of
elected judges, the ICJ Statute provides that the party may choose a qualified individual,
preferably from the list of nominees, to sit as a judge for that specific case.52
A U.S. national has always been among the elected judges on the court.53 Joan Donoghue, a U.S.
national who served on the court from 2010 to 2024, served as the ICJ’s president for her last
three years.54 Another U.S. national—Sarah Cleveland—was elected to the court upon
Donoghue’s completion of her final term.55 (Another sitting judge—Judge Nawaf Salam of

International Law, The Obama Administration and International Law (Mar. 25, 2010), https://2009-
2017.state.gov/s/l/releases/remarks/139119.htm.
43 See Exec. Order No. 13928, 85 Fed. Reg. 36139 (June 11, 2020).
44 See Exec. Order No. 14022, 86 Fed. Reg. 17895 (Apr. 7, 2021).
45 See Beth Van Schaak, Ambassador-at-Large for Global Criminal Justice, Statement of the United States at the 22nd
Session of the Assembly of States Parties of the International Criminal Court (Dec. 8, 2023), https://asp.icc-
cpi.int/sites/default/files/asp_docs/ASP22.GD_.USA_.07.12.-ENG.pdf.
46 Statute of the International Court of Justice art. 3, ¶ 1. The number of judges that hear and decide a particular case is
determined by the Court in accordance with the ICJ Statute. See id. arts. 24–29.
47 Id. art. 13, ¶ 1.
48 See id. arts. 4 ¶ 1 & 8. Candidates must get an absolute majority in each body to be elected to the court. See id. art.
10, ¶ 1.
49 Id. art. 4.
50 See id. arts. 4–6.
51 Id. art. 2.
52 Id. art. 31, ¶ 2.
53 All Members, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/all-members (last visited Feb. 23, 2024).
54 Biography of Joan Donoghue, INTERNATIONAL COURT OF JUSTICE (Feb. 8, 2021), https://www.icj-
cij.org/sites/default/files/donoghue_en.pdf.
55 Press Release, Antony J. Blinken, Sec’y of State, U.S. Dep’t of State, Election of Professor Sarah H. Cleveland to the
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Lebanon—was elected by the ICJ judges to serve as president of the ICJ after Donoghue’s
departure.56)
The ICC
The ICC has 18 judges who are nominated and elected by the states parties to the Rome Statute
for nine-year terms.57 Once elected, judges are assigned to sit on one of the ICC’s three divisions:
the Pre-Trial Chamber, the Trial Chamber, and the Appeals Chamber.58 Additionally, the Rome
Statute established the ICC’s Office of the Prosecutor, which “act[s] independently as a separate
organ of the Court.”59 The Prosecutor and deputy prosecutors are also elected by the states parties
for nine-year terms. The court’s current Prosecutor is Karim Khan, a United Kingdom national.60
(Because the United States is not a party to the Rome Statute,61 it does not vote in the elections of
the judges and prosecutors or in other matters related to the parties’ ongoing management of the
court.)
Jurisdiction
The jurisdiction of the ICJ and the ICC is specified in each court’s respective originating treaty.
The contours of each court’s jurisdiction reflect the distinct purposes states created the court to
serve in the international system.
The ICJ’s subject matter jurisdiction (often referred to in international law as “jurisdiction ratione
materiae”) is much broader than that of the ICC. While the ICJ Statute provides the ICJ with the
authority to decide any question of international law when states have consented to its
jurisdiction,62 the Rome Statute authorizes the ICC to investigate, prosecute, and try individuals
for four international crimes: genocide, crimes against humanity, war crimes, and the crime of
aggression.63
Each court’s originating treaty provides that the ICJ and the ICC may decide questions within
their subject matter jurisdiction only if they also have jurisdiction over the particular case that
presents those questions, discussed in the following two sections.

International Court of Justice (Nov. 9, 2023), https://www.state.gov/election-of-professor-sarah-h-cleveland-to-the-
international-court-of-justice/. See also Press Release, United Nations, Security Council Elects Five Judges to
International Court of Justice After Five Rounds of Voting (Nov. 9, 2023),
https://press.un.org/en/2023/sc15485.doc.htm.
56 Presidency, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/presidency (last visited Mar. 6, 2024).
57 Rome Statute, supra note 15, art. 36; see also International Criminal Court, Current Judges, https://www.icc-
cpi.int/judges/judges-who-s-who (last visited Feb. 23, 2024).
58 Rome Statute, supra note 15, art. 39. The number of judges assigned to each chamber and the way in which they are
assigned is also governed by the Rome Statute. See id.
59 Id. art. 42.
60 Karim A.A. Khan KC: Prosecutor, INTERNATIONAL CRIMINAL COURT, https://www.icc-cpi.int/about/otp/who-s-
who/karim-khan (last visited Mar. 6, 2024).
61 See States Parties to the Rome Statute, supra note 25.
62 Statute of the International Court of Justice art. 36, ¶ 2. Specifically, the ICJ has jurisdiction to decide matters
involving the interpretation of a treaty; any question of international law; the existence of any fact which, if established,
would constitute a breach of an international obligation; and the nature or extent of the reparation to be made for the
breach of an international obligation. Id.
63 Rome Statute, supra note 15, art. 5.
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The ICJ’s Case Jurisdiction
Since it began its work in 1946, the ICJ has decided numerous cases raising diverse issues of
international law64—from maritime and land boundary disputes65 to the legality of the use of
force and of certain weapons66—and has addressed many questions regarding the meaning of
various treaty provisions.67 The court’s docket has become increasingly busy over time;68 it
currently has 22 pending cases.69 The three most recently filed cases as of this writing are
Ukraine v. Russian Federation (filed in 2022),70 South Africa v. Israel (filed in 2023),71 and
Nicaragua v. Germany (filed in 2024).72 All three involve allegations that the defendant states
violated provisions of the Convention on the Prevention and Punishment of the Crime of
Genocide,73 and Nicaragua v. Germany also includes allegations of violations of international
humanitarian law (also referred to as the “law of war” or “law of armed conflict”).74
Only states—either individually or collectively in their capacity as members of the Security
Council, General Assembly, or other U.N. body—have standing before the ICJ.75 The ICJ may
decide any question of international law that is properly submitted for its resolution, which

64 See List of All Cases, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/list-of-all-cases (last visited Apr. 1,
2024).
65 See, e.g., Case Concerning Maritime Dispute (Peru v. Chile), Judgment, 2014 I.C.J. 4 (Jan. 27); Case Concerning the
Frontier Dispute (Benin v. Niger), Judgment, 2005 I.C.J. 90 (July 12).
66 See, e.g., Case Concerning Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United
States), Judgment, 1984 I.C.J. 392 (Nov. 26); Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion,
1996 I.C.J. 226 (July 8).
67 See, e.g., Case Concerning Application of the Convention on the Prevention and Punishment of the Crime of
Genocide (Bosnia v. Serbia), Judgment, 2007 I.C.J. 42 (Feb. 26); Whaling in the Antarctic (Australia v. Japan),
Judgment, 2014 I.C.J. 228 (Mar. 31).
68 Cf., e.g., Robert P. Alford, The Proliferation of International Courts and Tribunals: International Adjudication in
Ascendance, 162 AM. SOC. INT’L L. PROC. 160, 160 (2000) (“The past two decades have seen an explosion of new
international courts and tribunals. . . . Moreover, international courts and tribunals are being utilized with greater and
greater frequency.”).
69 See Pending Cases, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/pending-cases (last visited Apr. 1,
2024).
70 Allegations of Genocide Under the Convention on the Prevention and Punishment of the Crime of Genocide
(Ukraine v. Russian Federation), Application Instituting Proceedings, 2022 I.C.J. (Feb. 26, 2022), https://www.icj-
cij.org/sites/default/files/case-related/182/182-20220227-APP-01-00-EN.pdf. For a list of all of the filings, orders, and
press releases for the case, see International Court of Justice, Allegations of Genocide Under the Convention on the
Prevention and Punishment of the Crime of Genocide (Ukraine v. Russian Federation), https://www.icj-
cij.org/case/182 (last visited Apr. 1, 2024).
71 Application of the Convention on the Prevention and Punishment of the Crime of Genocide in the Gaza Strip (South
Africa v. Israel), Application Instituting Proceedings, 2023 I.C.J. (Dec. 28, 2023), https://www.icj-
cij.org/sites/default/files/case-related/192/192-20231228-app-01-00-en.pdf. For a list of all of the filings, orders, and
press releases for the case, see Application of the Convention on the Prevention and Punishment of the Crime of
Genocide in the Gaza Strip (South Africa v. Israel), INTERNATIONAL COURT OF JUSTICE, https://www.icj-
cij.org/case/192 (last visited Apr. 1, 2024).
72 Republic of Nicaragua v. Federal Republic of Germany, Application Instituting Proceedings, 2024 I.C.J. (Mar. 1,
2024), https://www.icj-cij.org/sites/default/files/case-related/193/193-20240301-app-01-00-en.pdf.
73 Convention on the Prevention of Punishment of the Crime of Genocide, Dec. 9, 1948, 102 Stat. 3045, 78 U.N.T.S.
277.
74 See What Is International Humanitarian Law?, INT’L COMM. OF THE RED CROSS (Apr. 6, 2022),
https://www.icrc.org/en/document/what-international-humanitarian-law (explaining that international humanitarian law
“protects persons who are not, or are no longer, directly or actively participating in hostilities, and imposes limits on the
means and methods of warfare” and “is made up primarily of treaties, customary international law and general
principles of law”).
75 See Statute of the International Court of Justice art. 34, ¶ 1.
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requires that states manifest their consent to its jurisdiction over a given case in one of the ways
provided for in the ICJ Statute. The ICJ has two types of case jurisdiction: contentious and
advisory.
Contentious Jurisdiction
The ICJ’s jurisdiction to decide disputes between states, known as its contentious jurisdiction, is
based on the consent of all states that are parties to the case. Any member state of the United
Nations (which is automatically a party to the ICJ Statute76) may consent to the court’s
jurisdiction to decide disputes between it and other member states, in one of several ways
described below.77 (A non-party state’s ability to bring cases before the court is dictated by the
Security Council.78)
Over the court’s history, the United States has brought nine cases against other states and has had
sixteen cases filed against it by other states.79 Congress has urged the executive branch to bring a
contentious case before the ICJ in at least one instance. In 1996, Congress made various findings
regarding allegations of terrorism committed by the Cuban government and “urge[d] the
President to seek, in the International Court of Justice, indictment for this act of terrorism.”80 (The
United States never filed such a case.81)
States may provide their consent to the court’s contentious jurisdiction in one of three ways:
consent to the ICJ’s compulsory jurisdiction, consent to its jurisdiction to resolve disputes about a
treaty, and consent to its jurisdiction to resolve a specific dispute.
Consent to Compulsory Jurisdiction
First, states may recognize the ICJ’s “compulsory” jurisdiction by depositing an instrument with
the court accepting its jurisdiction over any legal disputes with another state that has also
accepted the court’s compulsory jurisdiction.82 The United States was among the first states to
accept the court’s compulsory jurisdiction: On August 14, 1946, after securing Senate advice and

76 See U.N. Charter art. 93, ¶ 1.
77 See Statute of the International Court of Justice arts. 35, ¶ 1 & 36 ¶¶ 1−2.
78 See id. art. 4, ¶ 3.
79 See Contentious Cases Organized by State: United States, INTERNATIONAL COURT OF JUSTICE, https://www.icj-
cij.org/cases-by-country/us (last visited Feb. 23, 2024) [hereinafter U.S. ICJ Contentious Cases].
80 Cuban Liberty and Democratic Solidarity Act of 1996, Pub. L. No. 104-114, 110 Stat. 785.
81 See U.S. ICJ Contentious Cases, supra note 79.
82 See Statute of the International Court of Justice art. 36, ¶ 2.
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consent,83 President Truman deposited the U.S. instrument of acceptance.84 Four decades later, the
United States withdrew its declaration85 after the ICJ determined that it had jurisdiction over a
case that Nicaragua brought against the United States alleging that it had violated various
international legal prohibitions regarding the use of force against another state.86 In announcing
the U.S. withdrawal, the Reagan Administration maintained that the court did not have
jurisdiction and that the case was “a misuse of the Court for political purposes.”87 As of March
2024, there are 74 countries that currently consent to the ICJ’s compulsory jurisdiction.88
Consent to Jurisdiction over Disputes About a Treaty
Second, states may consent to the ICJ’s jurisdiction through treaty provisions. The ICJ Statute
provides the court with jurisdiction over disputes between states where a treaty provides that the
ICJ may resolve disputes about the meaning or application of the treaty (often referred to as
“compromissory clauses”).89 Numerous treaties include such clauses 90 and most of the ICJ’s
contentious-case jurisdiction to date has been treaty-based,91 including most of those cases to
which the United States has been a party.92

83 S. RES. 196, 79th Cong. (1946). In its report accompanying the resolution, the Senate Committee on Foreign
Relations explained its reasoning for choosing to use the treaty approval process rather than another method such as
majority votes by both houses even though the U.S. acceptance of the ICJ’s compulsory jurisdiction was not a formal
treaty like the U.N. Charter:
Inasmuch as the declaration would involve important new obligations for the United States, the
committee was of the opinion that it should be approved by the treaty process, with two-thirds of
the Senators present concurring. The force and effect of the declaration is that of a treaty, binding
the United States with respect to those states which have or which may in the future deposit similar
declarations. . . . While the declaration can hardly be considered a treaty in the strict sense of that
term, the nature of the obligations assumed by the contracting parties are such that no action less
solemn or less formal than that required for treaties should be contemplated.
ELBERT THOMAS, INTERNATIONAL COURT OF JUSTICE: REPORT TO ACCOMPANY S. RES. 196, S. Rep. No. 79-1835, at 10
(1946).
84 Declaration Recognizing as Compulsory the Jurisdiction of the Court, Aug. 14, 1946, 61 Stat. 1218, 1 U.N.T.S. 9.
States may and often do, however, qualify their acceptance of the ICJ’s jurisdiction by attaching what are known as
“reservations, declarations, and understandings” to their instruments of acceptance. See CRS In Focus IF12208,
Reservations, Understandings, Declarations, and Other Conditions to Treaties, by Steve P. Mulligan (2022). The
Senate attached three such qualifications to its approval of the U.S. acceptance of the ICJ’s compulsory jurisdiction,
including that the United States did not accept the ICJ’s jurisdiction over “disputes with regard to matters which are
essentially within the domestic jurisdiction of the United States as determined by the United States.” S. RES. 96, supra
note 83.
85 Termination of Declaration Recognizing as Compulsory the Jurisdiction of the Court, Apr. 7, 1986, 1408 U.N.T.S.
270.
86 See Case Concerning Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United States),
Judgment, 1984 I.C.J. 392, 442, ¶ 113 (Nov. 26).
87 Text of U.S. Statement on Withdrawal from Case Before the World Court, N.Y. TIMES (Jan. 19, 1985),
https://timesmachine.nytimes.com/timesmachine/1985/01/19/225996.html?pageNumber=4.
88 Declarations Recognizing the Jurisdiction of the Court as Compulsory, INTERNATIONAL COURT OF JUSTICE,
https://www.icj-cij.org/declarations (last visited Apr. 1, 2024).
89 Statute of the International Court of Justice art. 36, ¶ 1.
90 See Treaties, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/treaties (last visited Apr. 1, 2024).
91 See Contentious Cases, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/contentious-cases (last visited
Apr. 1, 2024).
92 See id.
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Although much of the ICJ’s treaty-based jurisdiction to date has been based on compromissory
clauses in bilateral treaties, a number have also been brought under multilateral treaties.93 Among
the multilateral treaties that have provided the basis for the court’s jurisdiction are the Vienna
Convention on Consular Relations,94 the International Convention on the Elimination of All
Forms of Racial Discrimination,95 and the International Convention for the Suppression of the
Financing of Terrorism.96 Five of the court’s pending cases are based on the compromissory
clauses of multilateral treaties to which the United States is a party.97 Four of those cases were
brought pursuant to the compromissory clause of the Convention on the Prevention and
Punishment of the Crime of Genocide:98 The Gambia v. Myanmar,99 Ukraine v. Russian
Federation,100 South Africa v. Israel,101 and Nicaragua v. Germany.102 The fifth, Canada and the
Netherlands v. Syrian Arab Republic,103 was brought pursuant to the compromissory clause of the
Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment.104
Consent to Jurisdiction over a Specific Dispute
Third, states may consent to the ICJ’s jurisdiction over a particular dispute by105—in the words of
the ICJ Statute, “special agreement.”106 For example, in 1981, the United States and Canada
invoked this type of ICJ jurisdiction by entering into an agreement referring to the court a dispute

93 See id.
94 See Case Concerning Avena and Other Mexican Nationals (Mexico v. United States), Judgment, 2004 I.C.J. 12 (Mar.
31).
95 See Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Armenia
v. Azerbaijan), Order, 2021 I.C.J. 362 (Dec. 7).
96 See Application of the International Convention for the Suppression of the Financing of Terrorism and of the
International Convention on the Elimination of All Forms of Racial Discrimination (Ukraine v. Russia), Order, 2017
I.C.J. 106 (April 19).
97 The United States is also party to the Vienna Convention on Consular Relations, Apr. 24, 1963, 596 U.N.T.S. 261
(VCCR), a treaty that does not contain a compromissory clause but instead allows states parties to agree to the ICJ’s
jurisdiction over disputes about the Convention by becoming parties to a separate treaty known as the Optional
Protocol to the Vienna Convention on Consular Relations Concerning the Compulsory Settlement of Disputes, Apr. 24,
1963, 596 U.N.T.S. 487. Although the United States ratified the Optional Protocol in 1969, President George W. Bush
withdrew the United States from the Optional Protocol in 2005. See U.N. Treaty Collection Depositary, Optional
Protocol to the Vienna Convention on Consular Relations Concerning the Compulsory Settlement of Disputes,
https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=III-8&chapter=3. The United States remains
a party to the VCCR, however. See U.N. Treaty Collection Depositary, Vienna Convention on Consular Relations,
https://treaties.un.org/Pages/ViewDetails.aspx?src=IND&mtdsg_no=III-6&chapter=3&clang=_en.
98 Convention on the Prevention of Punishment of the Crime of Genocide, art. IX, Dec. 9, 1948, 102 Stat. 3045, 78
U.N.T.S. 277.
99 See Application Instituting Proceedings and Request for Provisional Measures (Gambia v. Myanmar), 2019 I.C.J.
No. 178 (Nov. 11).
100 See supra note 70.
101 See supra note 71.
102 See supra note 72.
103 See Application of the Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or
Punishment (Canada and the Netherlands v. Syrian Arab Republic), Joint Application Instituting Proceedings, 2023
I.C.J. (June 8, 2023).
104 Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, art. 30, Dec. 10,
1984, T.I.A.S. No. 94-1120.1, 1465 U.N.T.S. 85.
105 Statute of the International Court of Justice art. 36, ¶ 1.
106 Id. art. 40, ¶ 1.
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between the countries regarding a maritime boundary; the court issued its decision on the proper
delimitation of the boundary under the governing international law in 1984.107
Advisory Jurisdiction
In addition to contentious jurisdiction, the ICJ Statute provides the court with advisory
jurisdiction to decide certain questions of international law that are not raised by a dispute
between states, but rather that are submitted to the court by the Security Council, General
Assembly, or other U.N. body.108 The Security Council and the General Assembly may ask the
court to provide an advisory opinion “on any legal question,”109 and other U.N. bodies may, if
authorized by the General Assembly, request an advisory opinion “on legal questions arising
within the scope of their activities.”110
The Security Council has invoked the ICJ’s advisory jurisdiction once: In 1970, the Council
asked the court to decide whether the continued presence of the South African government in
Namibia was illegal under international law.111 (The court determined that it was.112) The General
Assembly has submitted 18 requests for advisory opinions.113 In April 2023, for example, the
General Assembly asked the court to determine states’ obligations under international law related
to climate change.114 Five other U.N. bodies have requested advisory opinions.115 For example, in
November 2023, the International Labor Organization (ILO) asked the court to determine
whether the right to strike is protected by one of the ILO Conventions.116
In 1962, Congress expressed its support of one of ICJ’s early advisory opinions addressing a
question submitted by the General Assembly.117 The court determined that costs incurred in
undertaking U.N. operations in the Congo qualified as expenses that could be assessed to U.N.
members under the U.N. Charter.118 Specifically, Congress stated its sense that the ICJ’s decision
“provid[es] a sound basis for obtaining prompt payment of assessments for such expenditures”119
and that “the United Nations should take immediate steps to give effect to the advisory opinion of
the International Court of Justice on the financial obligations of members of the United Nations in
order to assure prompt payment of all assessments, including assessments to cover the cost of
operations to maintain or restore international peace and security.”120

107 Case Concerning Delimitation of the Maritime Boundary in the Gulf of Maine Area (Canada/United States),
Judgment, 1984 I.C.J. 246 (Oct. 12).
108 See U.N. Charter art. 96; Statute of the International Court of Justice art. 65.
109 U.N. Charter art. 96, ¶ 1.
110 U.N. Charter art. 96, ¶ 2.
111 See Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa)
Notwithstanding Security Council Resolution 276, Advisory Opinion, 1971 I.C.J. 16 (June 21).
112 See id. at 46.
113 See Organs and Agencies Authorized to Request Advisory Opinions, INTERNATIONAL COURT OF JUSTICE,
https://www.icj-cij.org/organs-agencies-authorized (last visited Mar. 7, 2024) [hereinafter ICJ Advisory Opinion
Requests].
114 Obligations of States in Respect of Climate Change, Request for Advisory Opinion, 2023 I.C.J. No. 187 (Apr. 12).
115 See ICJ Advisory Opinion Requests, supra note 113.
116 Right to Strike Under ILO Convention No. 87, Request for Advisory Opinion, 2023 I.C.J. (Nov. 10).
117 United Nations Loan Authorization Act, Pub. L. No. 87-731, 76 Stat. 695 (1962).
118 Certain Expenses of the United Nations, Advisory Opinion, 1962 I.C.J. 151 (July 20).
119 22 U.S.C. § 287k.
120 Id. § 287l.
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The ICC
The extent of the ICC’s subject matter jurisdiction—that is, which crimes it may investigate and
prosecute—depends on the way in which the ICC Prosecutor’s investigation of the case was
initiated. The ICC’s jurisdiction over allegations of one or more of the four Rome Statute
crimes121 depends on the event that prompts an investigation.122
Case Initiation by State Party Referral or by the ICC Prosecutor
First, a state party “may refer to the Prosecutor a situation in which one or more [of those] crimes
. . . appear to have been committed requesting the Prosecutor to investigate the situation.”123 The
ICC’s jurisdiction over crimes committed by Russian nationals in Ukrainian territory was
triggered in this manner: During the month following Russia’s February 2022 invasion of
Ukraine, 43 parties to the Rome Statute referred the situation to the ICC Prosecutor.124 On the
basis of these referrals, the Prosecutor opened the investigation in March 2022.125 That
investigation led the ICC Pre-Trial Chamber to issue arrest warrants for Russian President
Vladimir Putin and another official in his administration in March 2023,126 and a year later for
two Russian military commanders.127
Second, a case investigation can be initiated by the ICC Prosecutor proprio motu—that is, on the
Prosecutor’s own initiation rather than a referral—on the basis of information received regarding
allegations of the commission of Rome Statute crimes.128
When the ICC’s jurisdiction is triggered in one of these two ways—that is, either by state party
referral or by the ICC Prosecutor proprio motu—the reach of the court’s jurisdiction depends on
the crime alleged.
Genocide, Crimes Against Humanity, and War Crimes
For genocide, crimes against humanity, and war crimes, the ICC has jurisdiction if the crimes
were allegedly committed by a national of or on the territory of a state party to the Rome Statute
or a non-state party that has accepted the court’s jurisdiction.129 This means that there may be
cases in which the Rome Statute provides the ICC with jurisdiction over the nationals of non-state
parties that have not accepted the court’s jurisdiction in a given case. More specifically, the court

121 As noted, the ICC has subject matter jurisdiction for four crimes: genocide, crimes against humanity, war crimes,
and the crime of aggression. See Rome Statute, supra note 15, arts. 5−8 bis.
122 See Rome Statute, supra note 15, art. 13.
123 See id. arts. 13(a) & 14.
124 See Ukraine: Situation in Ukraine, INTERNATIONAL CRIMINAL COURT, https://www.icc-cpi.int/situations/ukraine
(last visited Feb. 28, 2024).
125 See Press Release, Karim A.A. Khan QC, ICC Prosecutor, ICC, Statement of ICC Prosecutor, Karim A.A. Khan
QC, on the Situation in Ukraine: Receipt of Referrals from 39 States Parties and the Opening of an Investigation (Mar.
2, 2022), https://www.icc-cpi.int/news/statement-icc-prosecutor-karim-aa-khan-qc-situation-ukraine-receipt-referrals-
39-states.
126 See Press Release, Piotr Hofmanski, President, ICC, Situation in Ukraine: ICC Judges Issue Arrest Warrants Against
Vladimir Vladimirovich Putin and Maria Alekseyevna Lvova-Belova (Mar. 17, 2023), https://www.icc-
cpi.int/news/situation-ukraine-icc-judges-issue-arrest-warrants-against-vladimir-vladimirovich-putin-and.
127 See Press Release, Karim A.A. Khan QC , ICC Prosecutor, ICC,, Statement by Prosecutor Karim A.A. Khan KC on
the Issuance of Arrest Warrants in the Situation in Ukraine (Mar. 5, 2024), https://www.icc-cpi.int/news/statement-
prosecutor-karim-aa-khan-kc-issuance-arrest-warrants-situation-ukraine.
128 See Rome Statute, supra note 15, arts. 13(c) & 15.
129 See id. arts. 12, ¶ 2 & 3.
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would have jurisdiction over cases in which the alleged crimes were committed by a non-state
party’s nationals in the territory of a state party or a non-state party that has accepted the court’s
jurisdiction. For example, the ICC has jurisdiction to investigate the alleged commission of
genocide, crimes against humanity, or war crimes by any country’s nationals in Ukraine and in
Gaza because, respectively, Ukraine, although not a state party, has accepted the court’s
jurisdiction for that purpose,130 and Palestine is a party to the Rome Statute.131 As a result, despite
the fact that neither Russia nor Israel is a party to the Rome Statute, their nationals are subject to
prosecution by the ICC in these investigations based on the consent of the states where the
alleged crimes were committed.132
Crime of Aggression
The ICC’s jurisdiction is more limited for the crime of aggression when the investigation is
initiated by state party referral or by the ICC Prosecutor propio motu.133 In such cases, in contrast
to genocide, crimes against humanity, and war crimes, the Rome Statute (1) permits state parties
to opt out of the ICC’s jurisdiction over the crime of aggression committed by the party’s
nationals,134 and (2) prohibits the court from exercising jurisdiction over the national of a non-
state party or over crimes committed in the territory of a non-state party.135 The ICC’s jurisdiction
over the crime of aggression was not activated in the Rome Statute, but rather later by an
amendment that entered into force in 2013.136 The United States participated in those negotiations
as a non-state party observer.137
Case Initiation by Security Council Referral
The third and final way an ICC investigation can be triggered is by referral from the Security
Council.138 Specifically, the Council may issue a resolution referring a situation in which one or
more of the Rome Statute crimes appear to have been committed to the ICC Prosecutor pursuant
to the Council’s authority under Chapter VII of the U.N. Charter139 to take measures in response
to what the Council determines is a “threat to the peace, breach of the peace, or act of
aggression.”140

130 See Letter from Pavlo Klimkin, Minister for Foreign Affairs of Ukraine, to Herman von Hebel, Registrar,
International Criminal Court (Sept. 8, 2015), https://www.icc-cpi.int/sites/default/files/iccdocs/other/Ukraine_Art_12-
3_declaration_08092015.pdf#search=ukraine [hereinafter Ukraine Acceptance of ICC Jurisdiction].
131 See State of Palestine, INTERNATIONAL CRIMINAL COURT (updated July 23, 2019), https://asp.icc-cpi.int/states-
parties/asian-states/Palestine.
132 See States Parties to the Rome Statute, supra note 25.
133 See Rome Statute, supra note 15, art. 15 bis, ¶ 1.
134 See id. art. 15 bis, ¶ 4.
135 See id. art. 15 bis, ¶ 5.
136 See ICC, Assembly of State Parties to the Rome Statute, Review Conference, The Crime of Aggression, ICC Doc.
RC/Res.6 (June 11, 2010); Amendments on the Crime of Aggression to the Rome Statute of the International Criminal
Court, UNITED NATIONS TREATY COLLECTION,
https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XVIII-10-b&chapter=18&clang=_en (last
visited Mar. 7, 2024).
137 Press Release, Dep’t of State, U.S. Delegation to Attend the Rome Statute Review Conference in Kampala (May 28,
2010), https://2009-2017.state.gov/r/pa/prs/ps/2010/05/142358.htm.
138 See Rome Statute, supra note 15, art. 13(b).
139 See id.
140 U.N. Charter art. 39. Chapter VII of the U.N. Charter provides that the Security Council “shall determine the
(continued...)
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None of the limitations on the ICC’s subject matter jurisdiction in cases that are initiated by state
party referral or by the ICC Prosecutor apply in cases initiated by Security Council referral.141
Instead, the ICC has jurisdiction over all the Rome Statute crimes when a Security Council
referral is made, including the crime of aggression, regardless of where they occurred or the
nationality of the alleged offender. To date the Security Council has issued two resolutions
referring situations to the ICC for investigation: the conflicts in Darfur, Sudan, in March 2005142
and in Libya in February 2011.143 Conversely, the Security Council may also require that the ICC
defer an investigation or prosecution for 12 months under the Council’s Chapter VII authority.144
As a permanent member of the Security Council, the United States has the power to prevent any
Council resolution from passing.145 Thus, as a practical matter, no ICC investigation will be
initiated through Security Council referral if the United States or one of the other four permanent
members of the Council (China, France, Russia, and the United Kingdom146) chooses to cast a
negative vote—known as the permanent members’ “veto” power—with respect to a resolution of
referral.147 Permanent members may also allow a resolution that otherwise has sufficient support
to pass without casting an affirmative vote by abstaining.148 The United States chose this
abstention option, for example, in the case of the Council’s resolution referring the situation in
Darfur to the ICC.149 On the other hand, the United States cast an affirmative vote in favor of the
Security Council resolution referring the situation in Libya to the ICC.150 To date there has been
one instance in which a proposed Security Council ICC referral resolution has failed to pass due

existence of any threat to the peace, breach of the peace, or act of aggression and shall make recommendations, or
decide what measures shall be taken in accordance [with Chapter VII] to maintain or restore international peace and
security”). Id.
141 See Rome Statute, supra note 15, art. 15 ter.
142 S.C. Res 1593 (Mar. 31, 2005).
143 S.C. Res 1970 (Feb. 26, 2011).
144 Rome Statute, supra note 15, art. 16.
145 See U.N. Charter arts. 23, ¶ 1 & 27, ¶ 3.
146 See id. art. 23, ¶ 1.
147 See id. arts. 23, ¶ 1 & 27, ¶ 3; Security Council, Voting System, U.N.,
https://www.un.org/securitycouncil/content/voting-system (last visited Mar. 7, 2024) [hereinafter Security Council
Voting]. The Security Council has a total of fifteen members. Id. art. 23, ¶ 1. In addition to the five permanent
members, ten members are elected by the General Assembly to serve on the Council for two-year terms. See U.N.
Charter art. 23. ¶¶ 1−2.
148 See Security Council Voting, supra note 147.
149 See Press Release, Security Council, Security Council Refers Situation in Darfur, Sudan, to Prosecutor of
International Criminal Court (Mar. 31, 2005), https://press.un.org/en/2005/sc8351.doc.htm. The United States agreed to
abstain rather than cast a negative vote after Council members agreed to add language to the resolution limiting the
ICC’s jurisdiction over non-state parties’ nationals in the case. See Nicholas Burns, Under Sec’y for Political Affairs,
U.S. Dep’t of State, Remarks to the Press on Sudan (Apr. 1, 2005), https://2001-
2009.state.gov/p/us/rm/2005/44138.htm. In the wake of the vote, the George W. Bush Administration explained its
decision to abstain resulted from a balancing of its strong support for accountability for atrocity crimes in Sudan on the
one hand, and its concerns about the ICC on the other. See id.
150 The Security Council unanimously voted in favor of the resolution referring the situation in Libya. See Press
Release, Security Council, In Swift, Decisive Action, Security Council Imposes Tough Measures on Libyan Regime,
Adopting Resolution 1970 in Wake of Crackdown on Protesters (Feb. 26, 2011),
https://press.un.org/en/2011/sc10187.doc.htm. In May of 2023, the Legal Adviser for the U.S. Mission to the United
Nations commended the ICC’s work after ICC Prosecutor Karim Khan briefed the Security Council on the Libya case.
See Mark Simonoff, Legal Adviser, U.S. Mission to the United Nations, Remarks at a UN Security Council Briefing on
Libya (May 11, 2023), https://usun.usmission.gov/remarks-at-a-un-security-council-briefing-on-libya-14/ (“The
International Criminal Court has an important role to play in the international system of justice, and the work of the
ICC in Libya plays a critical role in support of our collective pursuit of accountability, peace, and security.”).
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to a permanent member veto. In 2014, China and Russia used their veto power to prevent passage
of a Council resolution referring the situation in Syria to the ICC.151
The ICC Jurisdiction in Practice: Investigation of Crimes Committed in
Ukraine
The ICC’s jurisdiction in its ongoing investigation of Rome Statute crimes alleged to have been
committed in Ukrainian territory is illustrative of the differences in the reach of the ICC’s
jurisdiction that depend on the way the case is initiated and what the crime alleged is. The ICC
has jurisdiction to investigate the commission of crimes against humanity and war crimes on
Ukrainian territory (including by Russian nationals, even though Russia is not an ICC party)
because (1) Ukraine, although not a state party to the Rome Statute, has accepted the ICC’s
jurisdiction for those crimes committed in its territory from 2014 on;152 and (2) several states
parties referred the Ukraine situation to the ICC Prosecutor.153
Because the Rome Statute prohibits the ICC from exercising jurisdiction over the alleged
commission of the crime of aggression by non-state party nationals absent Security Council
referral, the ICC’s investigation may not include the crime of aggression unless it receives a
referral from the Security Council. Russia’s veto power as a permanent Security Council member,
however, effectively precludes that jurisdictional avenue.154
Effect of Decisions & Enforcement Mechanisms
In contrast to domestic legal systems, there are no centralized mechanisms for enforcing the
decisions of international courts such as the ICJ and the ICC. Rather, international courts are
dependent on the states that created them—individually and collectively—to comply with,
support, and enforce their decisions.
The ICJ
Contentious Cases
The ICJ’s decisions in contentious cases are binding solely on the parties to the dispute in a given
case.155 The U.N. Charter obligates member states to comply with any ICJ decision to which they
are a party.156 In the event that a state refuses to comply with an ICJ judgment that is binding on
it, the other state that is a party to the case may seek recourse with the Security Council, which is
authorized to take measures to enforce the court’s judgment.157 As with a Security Council ICC
referral or any other Council action, however, such enforcement measures are possible only if all
five permanent members agree to vote in their favor or to abstain.158 The Security Council has

151 See Press Release, Security Council, Referral of Syria to International Criminal Court Fails as Negative Votes
Prevent Security Council from Adopting Draft Resolution (May 22, 2014),
https://press.un.org/en/2014/sc11407.doc.htm.
152 See Ukraine Acceptance of ICC Jurisdiction, supra note 130.
153 See supra notes 124 & 125 and accompanying text.
154 See U.N. Charter art. 23 ¶ 1; supra note 147 and accompanying text.
155 Statute of the International Court of Justice art. 59.
156 U.N. Charter art. 94, ¶ 1.
157 See id. art. 94, ¶ 2.
158 See supra notes 145-148 and accompanying text.
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never taken action to enforce an ICJ judgment, and there has been only one instance in which a
state asked the Security Council to do so.159 In 1986, Nicaragua requested that the Council
enforce the ICJ’s judgment against the United States in Case Concerning Military and
Paramilitary Activities In and Against Nicaragua (Nicaragua v. United States).160 The United
States vetoed the subsequent proposed Security Council resolution “call[ing] for full and
immediate compliance” with the ICJ’s judgment in the case.161
In the absence of Security Council enforcement measures, states may individually and
collectively attempt to induce compliance with ICJ judgments by taking various actions,
including calling on a state to comply with the judgment against it in diplomatic channels or
issuing economic sanctions or other countermeasures. The United States was among several
countries that took such action, for example, with respect to the ICJ’s provisional measures order
(akin to a preliminary injunction at the domestic level162) in the 2022 case brought by Ukraine
against Russia, which directed Russia to “immediately suspend” its military operations in
Ukraine.163
Regardless of whether a state that is bound by an ICJ judgment complies with it, the court’s
analyses of and conclusions regarding international law in its opinions—including the meaning of
various treaty provisions that it is called upon to interpret—are considered to be highly persuasive
and authoritative by many states and the international community more broadly.164 In this respect,
ICJ decisions can have impacts beyond the actions of states in response to a particular judgment
by clarifying and contributing to the development of international law.165

159 In Hindsight: The Security Council and the International Court of Justice, SECURITY COUNCIL REPORT (Dec. 28,
2016), https://www.securitycouncilreport.org/monthly-forecast/2017-
01/in_hindsight_the_security_council_and_the_international_court_of_justice.php [hereinafter The Security Council
and the ICJ]. The ICJ determined that the United States was obligated to immediately cease its support of paramilitary
forces in their campaign against the Nicaraguan government and to make reparations to Nicaragua for the injuries it
suffered as a result of what the ICJ found to be multiple breaches of U.S. obligations under international law. See Case
Concerning Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United States), Merits
Judgment, 1986 I.C.J. 14, 149 (June 27), https://www.icj-cij.org/sites/default/files/case-related/70/070-19860627-JUD-
01-00-EN.pdf.
160 See Letter from Nora Astorga, Nicaragua U.N. Ambassador, to President, Security Council, U.N. Doc. S/185414
(Oct. 20, 1986), https://www.securitycouncilreport.org/atf/cf/%7B65BFCF9B-6D27-4E9C-8CD3-
CF6E4FF96FF9%7D/s_18415.pdf.
161 Congo, Ghana, Madagascar, Trinidad and Tobago and United Arab Emirates: Draft Resolution, U.N. Doc. S/18428
(Oct. 28, 1986), https://www.securitycouncilreport.org/atf/cf/%7B65BFCF9B-6D27-4E9C-8CD3-
CF6E4FF96FF9%7D/s_18428.pdf; see also The Security Council and the ICJ, supra note 159.
162 See generally Rüdiger Wolfrum, Interim (Provisional) Measures of Protection, in OXFORD PUBLIC INTERNATIONAL
LAW (2006), https://opil.ouplaw.com/display/10.1093/law:epil/9780199231690/law-9780199231690-e32 (explaining
the use of provisional measures by international courts).
163 Allegations of Genocide Under the Convention on the Prevention and Punishment of the Crime of Genocide
(Ukraine v. Russian Federation), Provisional Measures, 2022 I.C.J. 211, 213 (Mar. 16), https://www.icj-
cij.org/sites/default/files/case-related/182/182-20220316-ord-01-00-en.pdf; see, e.g., Press Release, Ned Price, Dept.
Spokesman, U.S. Dep’t of State, Welcoming the International Court of Justice’s Order Directing the Russian
Federation to Immediately Suspend Military Operations in Ukraine (Mar. 16, 2022), https://www.state.gov/welcoming-
the-international-court-of-justices-order-directing-the-russian-federation-to-immediately-suspend-military-operations-
in-ukraine/ (“We welcome the Court’s order and call on the Russian Federation to comply with the order, immediately
cease its military operations in Ukraine, and to establish unhindered humanitarian access in Ukraine.”)
164 See Press Release, U.N., International Court of Justice Docket Reflects Legal Questions Concerning All Humanity
in Every Region, President Says, as General Assembly Takes Up Report (Oct. 26, 2023),
https://press.un.org/en/2023/ga12547.doc.htm.
165 See id.; cf. also ICJ Statute, art. 56, ¶ 1 (requiring the ICJ “to state the reasons on which [its judgments are] based”).
ICJ decisions can contribute to the development of international law even though the impact they have within domestic
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Advisory Opinions
The ICJ’s advisory opinions are nonbinding,166 and thus cannot be directly enforced in the way its
judgments in contentious cases might be. However, like the ICJ’s contentious-case opinions, ICJ
advisory opinions are considered highly authoritative and thus influence the understanding and
development of international law.167 Further, state actors may still call for adherence to the court’s
advisory opinions, as Congress did in its resolution in support of the ICJ’s advisory opinion about
the contribution obligations of U.N. member states.168
The ICC
The ICC is similarly dependent on states to enforce its orders and judgments by, for example,
making arrests and transferring defendants to the ICC’s detention center, freezing alleged
offenders’ assets for potential use in damages awards, and carrying out sentences.169 States parties
to the Rome Statute are obligated to provide such assistance,170 but non-state parties may also
choose to provide various forms of assistance to the court. As noted, the United States has done
this periodically over time, including pursuant to statutory directives.171 Additionally, ICC
judgments that contain legal reasoning and conclusions can contribute to the clarification and
development of international criminal law.172
Conclusion
Although the U.S. relationship with the ICJ and the ICC over the course of each court’s existence
has been varied and often complex, the United States has often made efforts to engage with the
courts and to influence their operations. Congress has always played a role in the U.S.
relationship with these courts. In the case of both the ICJ and the ICC, Congress has done so
through its appropriations power173 and the Senate’s treaty advice-and-consent power.174 For

legal systems varies. The U.S. Supreme Court, for example, has held that an ICJ decision requiring the United States to
comply with its obligations under the Vienna Convention on Consular Relations was not enforceable in U.S. law
because no implementing legislation had been enacted. See Medellin v. Texas, 552 U.S. 491, 504-05, 510-11 (2008).
For a more in-depth discussion of the effect of international law on U.S. law, see CRS Report RL32528, International
Law and Agreements: Their Effect upon U.S. Law, by Steve P. Mulligan.
166 See Advisory Jurisdiction, INTERNATIONAL COURT OF JUSTICE, https://www.icj-cij.org/advisory-jurisdiction (last
visited Mar. 11, 2024).
167 See id.
168 See supra text accompanying notes 118–120.
169 See How the Court Works, INTERNATIONAL CRIMINAL COURT, https://www.icc-cpi.int/about/how-the-court-works
(last visited Mar. 11, 2024).
170 See Rome Statute, supra note 15, arts. 86–89, 91, 103, 105, & 109.
171 See supra text accompanying notes 38–40.
172 Cf. Rome Statute, supra note 15, arts. 74, ¶ 5 & 83, ¶ 4 (requiring the Trial and Appeals Chambers to issue decisions
that state the reasons on which they are based).
173 See CRS In Focus IF10354, United Nations Issues: U.S. Funding to the U.N. System, by Luisa Blanchfield (2023)
(noting that “[t]he United States is the single largest financial contributor to the United Nations,” and that “[t]he U.N.
regular budget funds the core administrative costs of the organization, including the . . . International Court of Justice”);
22 U.S.C. § 7401(b)) (prohibiting use of funds to support the ICC); supra note 40 and accompanying text (discussing
statutory authorization for State Department to provide certain forms of assistance to the ICC in a State Department
funding statute).
174See supra text accompanying notes 30–31; supra notes 83–85 and accompanying text. For a broader discussion of
Congress’s ability to influence international agreements, see CRS Legal Sidebar LSB11049, International Agreements
(Part II): Examining Tools for Congressional Influence Over International Instruments, by Steve P. Mulligan (2023).
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example, the Senate approved the U.S. status as a party to the ICJ by providing its advice and
consent to the U.N. Charter, and Congress constrained the executive branch from using funds to
provide assistance to the ICC on some matters and authorized the use of funds to help the ICC in
others. In the case of the ICJ, it has made recommendations to the Administration and to the
international community more broadly regarding the court’s cases.175 In the case of the ICC,
Congress has passed legislation that structures the U.S. relationship with the court in ways that
could assist or hinder its work.176
The roles that the ICJ and the ICC play in the international system, their structure, their respective
jurisdictional authorities, the mechanisms for enforcing their judgments, and the various U.S.
interactions with them over time may all provide Congress with useful lenses as it carries out its
legislative and oversight mandates related to the courts. More specifically, such considerations
support Congress’s continued evaluation of how the courts’ actions may impact the international
legal system in which the United States operates and pursues its various interests. As Congress
observes how the courts carry out their jurisdictional mandates, their impact on the development
of international law, and the Administration’s interactions with them, Congress may, as it has in
the past, accordingly constrain, authorize, or make recommendations to the executive branch in
its interactions with the ICJ and the ICC.

Author Information

Karen Sokol

Legislative Attorney

175 See supra text accompanying notes 117–120.
176 See supra text accompanying notes 34–40.
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Disclaimer
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under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
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