HALT Fentanyl Act
What does the HALT Fentanyl Act do?
S 331 is a Senate bill sponsored by Sen. Bill Cassidy (R-LA). The HALT Fentanyl Act permanently places all fentanyl-related substances as a class into Schedule I of the Controlled Substances Act, subjecting them to the same quantity-based mandatory minimum penalties that apply to fentanyl analogues under existing law. The law also creates a faster registration process for researchers who want to study Schedule I substances, including fentanyl, by allowing some research to begin as soon as 30 days after notifying the Attorney General.
Did S 331 pass? Where it stands
As of July 17, 2026, S 331 has been signed into law on July 16, 2025.
Status: Signed into Law
Latest vote: House Passed 321–104 on June 12, 2025
Outlook: Enacted
Enacted: Signed into law on July 16, 2025
Key provisions
- Class Scheduling of Fentanyl Variants
- Any substance structurally related to fentanyl by one of five defined chemical modifications is permanently placed in Schedule I
- Includes salts, isomers, and salts of isomers of any qualifying fentanyl-related substance
- Attorney General may publish a Federal Register list of qualifying substances; unlisted substances still qualify if they meet the structural definition
- Criminal Penalties for Fentanyl Variants
- Offenses involving fentanyl-related substances now trigger the same quantity-based mandatory minimums that apply to fentanyl analogues
- The specific quantity thresholds for each mandatory minimum tier are set by cross-reference to the existing analogue provisions in Section 401(b)(1) and are not restated in the bill
- Importation and exportation penalties under the Controlled Substances Import and Export Act also updated to include fentanyl-related substances
- Research Registration Reforms
- Researchers already registered for Schedule I or II research may begin fentanyl-related research 30 days after notifying the Attorney General
- New researchers without prior registration receive a registration decision within 45 days of submitting a notice
- Single registration now permitted for related research sites in the same city or county under the same institution
Last updated June 10, 2026