An Expiration Date for Temporary Control of Fentanyl Analogues

An Expiration Date for Temporary Control of Fentanyl Analogues

An Expiration Date for Temporary Control of Fentanyl Analogues

Updated June 9, 2025 (LSB10404)

In February 2020, the Temporary Reauthorization and Study of the Emergency Scheduling of Fentanyl Analogues Act temporarily placed certain fentanyl-related substances (FRS)—compounds chemically related to the powerful synthetic opioid fentanyl—in Schedule I of the Controlled Substances Act (CSA). Congress has since extended the temporary scheduling of FRS several times, and it is currently slated to expire on September 30, 2025. In light of the approaching expiration, Congress may be interested in the legal issues related to the scheduling of fentanyl analogues. This Legal Sidebar provides an overview of the legal framework that applies to fentanyl and its analogues, key considerations involved in scheduling fentanyl analogues, and options for pursuing scheduling via legislation.

The CSA and Controlled Substance Regulation

The CSA regulates drugs and other substances—whether medical or recreational, legally or illicitly distributed—that pose a risk of abuse and dependence. Substances become subject to the CSA through placement in one of five lists, known as Schedules I through V. Controlled substances in Schedule I are subject to the most stringent controls, reflecting a finding that a substance has a high potential for abuse and no currently accepted medical use. Substances in Schedules II through V have accepted medical uses and have been deemed to pose progressively lower risks of abuse and dependence.

Fentanyl itself is in Schedule II, as it has recognized medical uses related to pain management. Some specific substances chemically related to fentanyl are controlled in Schedule I if they do not have currently accepted medical uses or Schedule II if they do. By contrast, cough medicines containing small amounts of another opiate, codeine, are in Schedule V. (Many other prescription drugs are not controlled substances subject to the CSA.)

A substance not specifically designated for control in Schedules I through V may still be subject to the CSA as a controlled substance analogue. A controlled substance analogue is a substance not otherwise approved by the Food and Drug Administration (FDA) or scheduled under the CSA that has (1) a chemical structure substantially similar to that of a controlled substance in Schedule I or II or (2) an actual or intended effect that is "substantially similar to or greater than the stimulant, depressant, or hallucinogenic effect ... of a controlled substance in schedule I or II." A substance that meets those criteria and is intended for human consumption is treated as a controlled substance in Schedule I.

Unscheduled synthetic opioids related to fentanyl may qualify as controlled substance analogues. However, as a practical matter, regulating those substances as controlled substance analogues may allow for less effective control than if the substances are specifically scheduled under the CSA. The Department of Justice, which prosecutes CSA violations, has stated that controlled substance analogue prosecutions are fact-intensive and burdensome compared to prosecutions involving scheduled substances, because analogue cases raise "complex chemical and scientific issues" related to the molecular makeup and effect of each substance. Moreover, some synthetic drugs may not meet the applicable criteria to be deemed controlled substance analogues—for example, because their effects are unpredictable or because they replicate the effects of more than one class of drugs. As a result, some policymakers have expressed interest in formally scheduling fentanyl analogues.

Administrative and Legislative Scheduling Procedures

Either Congress or the Drug Enforcement Administration (DEA) administrator can place a substance in a CSA schedule, move a substance to a different schedule, or remove a substance from the schedules. Congress can take those scheduling actions through legislation. DEA, for its part, makes permanent scheduling decisions through a formal rulemaking process that involves participation by other agencies and the public. Before initiating scheduling proceedings, DEA must request a scientific and medical evaluation of the substance at issue. FDA prepares the evaluation, considering eight statutory factors primarily related to the effects of the substance and its potential for abuse, and recommends whether the substance should be controlled and, if so, in what schedule. FDA's scientific and medical factual findings are binding on DEA, and if FDA recommends against controlling the substance, DEA cannot schedule it. However, DEA has stated that it has "the final authority to schedule, reschedule, or deschedule a drug under the Controlled Substances Act."

Upon receipt of FDA's report, the DEA administrator evaluates all the relevant data and determines whether the substance should be scheduled, rescheduled, or removed from control. Before placing a substance in a schedule, the DEA administrator must make specific findings related to the substance's medical use and potential for abuse and dependence. DEA makes scheduling decisions through notice-and-comment rulemaking, meaning that interested parties must have the opportunity to submit comments, which the agency may need to respond to before the scheduling action becomes final. Once final, DEA scheduling decisions are subject to judicial review.

Permanent DEA scheduling decisions can take years to consider and finalize. Recognizing that in some cases faster scheduling may be appropriate, Congress also created a temporary scheduling procedure, allowing the DEA administrator to place a substance in Schedule I temporarily when "necessary to avoid an imminent hazard to the public safety." Before issuing a temporary scheduling order, the DEA administrator must provide 30 days' notice to the public and the Secretary of Health and Human Services (HHS) and consider any comments from the Secretary. In issuing a temporary scheduling order, the DEA administrator needs to consider three of the eight factors relevant to permanent scheduling: (1) the history and current pattern of abuse of the substance at issue; (2) the scope, duration, and significance of abuse; and (3) the risk to public health. A substance may be temporarily scheduled for up to two years. If permanent scheduling proceedings are pending, the DEA administrator may extend the temporary scheduling period for one additional year. Temporary scheduling orders are not subject to judicial review.

Temporary Scheduling of Fentanyl-Related Substances

On February 6, 2018, DEA issued a temporary scheduling order (Fentanyl TSO) that placed certain "fentanyl-related substances" in Schedule I for two years. While previous scheduling actions by both DEA and Congress generally identified specific substances or lists of several discrete substances for control, the Fentanyl TSO instead imposed controls on a broad class of "fentanyl-related substances" that met specific criteria related to their chemical structures. While the class of FRS is finite, it includes thousands of different chemicals. As one opioid researcher testified before Congress, the effects, potential for abuse and dependence, and medical utility of many of those substances are unknown.

Perhaps because of these uncertainties, DEA did not initiate permanent scheduling of the full class of FRS. January 2020 testimony from HHS suggested that, given the large number of FRS, it was not feasible for FDA and DEA to make the individualized findings required to permanently schedule each substance. Without such findings, administrative action to permanently schedule the full class of FRS could be vulnerable to challenge in court. Accordingly, stakeholders—including DEA and HHS—called on Congress to permanently schedule FRS through legislation. In the meantime, DEA has continued to take temporary and permanent scheduling actions with respect to certain specific fentanyl analogues, including some FRS subject to the Fentanyl TSO.

On February 6, 2020, in response to calls for legislative scheduling, Congress enacted the Temporary Reauthorization and Study of the Emergency Scheduling of Fentanyl Analogues Act. That legislation did not permanently schedule the class of FRS. Instead, it temporarily extended the Fentanyl TSO until May 6, 2021. Congress has since extended the temporary scheduling several times, most recently through September 30, 2025. Absent further legislative or administrative action, FRS will remain in Schedule I until that date and will be subject to all restrictions and penalties applicable to Schedule I substances. If the temporary scheduling expires, the full class of FRS will no longer be scheduled under the CSA, though they may still be subject to control as controlled substance analogues. Fentanyl itself and certain other related chemicals are permanently controlled in Schedules I and II. The temporary scheduling of FRS does not affect those classifications.

Considerations for Congress

If Congress pursues permanent scheduling of fentanyl analogues, several legal questions may arise.

Defining Substances Subject to Control

A key question when scheduling fentanyl analogues is how to define the substances subject to regulation. Not all fentanyl analogues have effects like those of fentanyl itself, and there are many whose effects are unknown. As discussed above, the Fentanyl TSO, as extended by Congress, defines covered FRS based on their chemical structure. Some have argued that this legal definition may be both overinclusive (because it may include inactive substances) and underinclusive (because it may exclude potentially dangerous opioids that are not chemically related to fentanyl or that involve chemical modifications not listed in the Fentanyl TSO). In light of those concerns, the Temporary Reauthorization and Study of the Emergency Scheduling of Fentanyl Analogues Act required the Comptroller General to conduct a study evaluating "the definition of the class of fentanyl-related substances." The study was published in April 2021.

Regulating fentanyl analogues using the Fentanyl TSO's definition of FRS is not the only option for Congress. Legislative proposals from the 116th-119th Congresses have offered differing approaches to scheduling fentanyl analogues. For instance, proposals such as the Stopping Overdoses of Fentanyl Analogues Act, the SAFE Act, and the HALT Fentanyl Act would permanently add to Schedule I the class of FRS defined in the Fentanyl TSO. The Modernizing Drug Enforcement Act of 2019 would have amended the CSA to add to Schedule I "mu opioid receptor agonists"—a class of opioids (including morphine) that is defined by the molecular reactions that produce their effects. The SIFT Act of 2023 would have scheduled certain specific fentanyl analogues, as well as the class of FRS defined in the Fentanyl TSO, and would also have provided a process for expedited rescheduling or descheduling of any FRS that were later found to pose little or no risk of abuse. The TEST Act from the 118th Congress and the SAFE Act would also provide an expedited rescheduling or descheduling process for FRS.

Criminal Enforcement and Sentencing

Another question related to the scheduling of fentanyl analogues is how those substances should fit into the CSA's criminal enforcement and sentencing regimes. Penalties for criminal violations of the CSA vary widely based on the substance at issue, with some penalties tailored to specific substances. Sentences also depend on numerous other factors, including the amount of the substance involved and the nature of the illicit activity (e.g., simple possession versus distribution). The CSA imposes mandatory minimum sentences for some offenses involving Schedule I controlled substances. No mandatory minimum penalty attaches to a first conviction for simple possession or manufacture, distribution, and possession with intent to distribute most Schedule I controlled substances. However, minimum sentences apply to second and subsequent offenses and offenses resulting in death or serious injury. And, under CSA provisions that predate the temporary scheduling of FRS, mandatory minimum sentences apply to the manufacture, distribution, and possession with intent to distribute large amounts of fentanyl or "any analogue" of fentanyl.

The CSA generally applies to offenses committed knowingly or intentionally. The Supreme Court has explained that prosecutors bringing charges under the CSA must prove that a defendant either knew he was dealing with "some unspecified substance listed on the federal drug schedules" or "knew the identity of the substance he possessed." For example, "a defendant who knows he is distributing heroin but does not know that heroin is listed on the schedules" satisfies the CSA's mental state requirement.

Applying these rules to legislation scheduling a class of fentanyl analogues raises a number of legal and policy issues. Some commentators have raised criminal justice concerns, asserting that individuals may face criminal liability for unwitting possession of fentanyl analogues or that Schedule I status may give rise to harsh mandatory minimum penalties under the CSA. On the other hand, some commentators and law enforcement officials seek more stringent controls of fentanyl analogues to combat the opioid crisis. As discussed above, difficulties in prosecuting activities involving unscheduled fentanyl analogues under the analogue controlled substance provisions of the CSA have led to calls for permanently placing FRS in Schedule I. While the Fentanyl TSO and subsequent legislation temporarily controlled FRS in Schedule I, they did not alter the CSA's sentencing regime or the mental state requirements that apply to controlled substance offenses. A January 2021 U.S. Sentencing Commission report examines in detail recent sentencing practices related to fentanyl and fentanyl analogues.

Recent legislative proposals would tailor how the CSA applies to fentanyl analogues. For instance, the Federal Initiative to Guarantee Health by Targeting Fentanyl Act and the SAFE Act would permanently schedule the class of FRS but provide that certain minimum terms of imprisonment do not apply to those substances. The SAFE Act would also allow for resentencing if a defendant is convicted of an offense involving an FRS that is later rescheduled or descheduled. By contrast, the Ending the Fentanyl Crisis Act of 2021 would have applied more stringent control to fentanyl analogues, imposing penalties for "scheduled or unscheduled" fentanyl analogues and reducing the amounts of those substances required to trigger mandatory sentences.

Research Access

While fentanyl analogues may pose public health risks, some contend that the substances may also offer medical benefits—including pain management and treatment of opioid dependence or overdose—and worry that placing fentanyl analogues in Schedule I may impede research into potential medical uses.

Although people sometimes colloquially refer to substances in Schedule I as "illegal drugs," the CSA does not fully ban any drugs or other substances. Schedule I controlled substances have no accepted medical use and thus may not be dispensed by prescription like other controlled substances. Nonetheless, it is legal to produce, dispense, and possess Schedule I substances in the context of federally approved scientific studies. At the same time, Schedule I status creates certain hurdles for would-be researchers, who must register with DEA and comply with the CSA's registration requirements, which include security and reporting obligations. The registration application process is more stringent for research involving substances in Schedule I than for other controlled substances, and security requirements are more stringent for substances in Schedule I or II.

The Comptroller General's 2021 report on control of fentanyl analogues included analysis of the potential effects of the class-wide scheduling of FRS on research. In addition, a number of recent legislative proposals would substantively alter the legal framework for research involving Schedule I controlled substances. For example, the SIFT Act of 2023, the TEST Act, the SAFE Act, and the HALT Fentanyl Act would relax certain registration requirements that apply to research on Schedule I controlled substances.