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. 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 certain schedule I research. 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.