Halt All Lethal Trafficking of Fentanyl Act or the HALT Fentanyl Act This bill permanently places fentanyl-related substances as a class into schedule I of the Controlled Substances Act. A schedule I controlled substance is a drug, substance, or chemical that has a high potential for abuse; has no currently accepted medical value; and is subject to regulatory controls and administrative, civil, and criminal penalties under the Controlled Substances Act. (The temporary scheduling order issued by the Drug Enforcement Administration to place fentanyl-related substances into schedule I of the Controlled Substances Act expires on December 31, 2024.) Under the bill, offenses involving fentanyl-related substances are triggered by the same quantity thresholds and subject to the same penalties as offenses involving fentanyl analogues (e.g., offenses involving 100 grams or more trigger a 10-year mandatory minimum prison term). Additionally, the bill establishes a new, alternative registration process for schedule I research that is funded by the Department of Health and Human Services or the Department of Veterans Affairs or that is conducted under an investigative new drug exemption from the Food and Drug Administration. The bill also makes several other changes to registration requirements for conducting research with controlled substances, including permitting a single registration for related research sites in certain circumstances, waiving the requirement for a new inspection in certain situations, and allowing a registered researcher to perform certain manufacturing activities with small quantities of a substance without obtaining a manufacturing registration. Finally, the bill expresses the sense that Congress agrees with the interpretation of Controlled Substances Act in United States v. McCray , a 2018 case decided by the U.S. District Court for the Western District of New York. In that case, the court held that butyryl fentanyl, a controlled substance, can be considered an analogue of fentanyl even though, under the Controlled Substances Act, the term controlled substance analogue specifically excludes a controlled substance.