Fifth Circuit Adopts Narrow Interpretation of Two Critical DEA Regulations

On February 13, 2026, the Fifth Circuit issued a unanimous panel opinion holding that the Drug Enforcement Agency (“DEA”) misinterpreted two of its pivotal regulations — its “corresponding responsibility” (21 C.F.R. § 1306.04(a)) and “usual course of professional practice” (21 C.F.R. § 1306.06) regulations.¹ The Fifth Circuit took a narrow view of both regulations in an opinion that rejected the DEA’s own longstanding interpretation of these regulations, which has been deferred to by other courts, and opened the door for potential future defense strategies.

The case involved the DEA’s deregistration of a Louisiana pharmacy, Neumann’s Pharmacy, following a hearing in which an administrative law judge (“ALJ”) found that Neumann’s did not properly resolve or document certain “red flags” indicating that certain prescriptions may have been invalid. The alleged red flags included prescriptions involving “drug cocktails” (combinations of controlled substances widely known to be abused or diverted) and “therapeutic duplication,” among other red flags that the DEA or Department of Justice (“DOJ”) typically cite to. The DEA adopted the ALJ’s recommendation and found such conduct violative of both the “corresponding responsibility” and “usual course of professional practice” regulations.²

The Fifth Circuit rejected the DEA’s interpretation of both regulations, vacating the deregistration order and remanding the case back to the DEA. First, the Fifth Circuit narrowly interpreted the “corresponding responsibility” regulation, which states that prescriptions for controlled substances must be issued “for a legitimate medical purpose by an individual practitioner acting in the usual course of his professional practice” and that “a corresponding responsibility rests with the pharmacist who fills the prescription” for ensuring the “proper prescribing and dispensing of controlled substances.”³ It further states that “the person knowingly filling” an invalid prescription “shall be subject to” penalties.⁴

The DEA has long interpreted this regulation as requiring a pharmacist to investigate common “red flags” and refuse to fill a prescription if the pharmacist knows, or has reason to know, that the prescription was not written for a legitimate medical purpose.⁵ But the Fifth Circuit rejected this long-held view in favor of a narrower interpretation that requires the DEA to demonstrate both prescription invalidity and that the pharmacist subjectively knew of its invalidity. And because the DEA did not show that any prescription was invalid at the time it was issued, the Fifth Circuit held the invalidity element was not met.

Further, the Fifth Circuit held that the DEA should have applied — but did not — a subjective standard to the knowledge element of the statute and left open the question of whether subjective knowledge under a “willful blindness” standard could suffice.

Turning to the second regulation at issue, the Fifth Circuit also rejected the DEA’s interpretation of what “usual course of professional practice” means as that phrase is used in 21 C.F.R. § 1306.06. The regulation requires a pharmacist to fill a prescription only “in the usual course of his professional practice.” The DEA interpreted this as incorporating relevant state law standards of care,⁶ which the Fifth Circuit found to be legal error. Noting that “course of professional practice” is a term of art under the Controlled Substances Act (“CSA”), the court held that the phrase means “filling prescriptions in good faith within the bona fide operations of a pharmacy,” even if the filling of the prescription may deviate from standards of care.⁷ The Fifth Circuit reasoned that to find otherwise would “convert every act of negligence under state law into a federal felony.”⁸

The Fifth Circuit’s interpretation of these two key DEA regulations stands in stark contrast to the DEA’s own interpretation. This narrower interpretation has the potential to impose significant burdens on the government in both administrative DEA proceedings and civil DOJ matters predicated on these CSA regulations, particularly if the government must prove the invalidity of underlying prescriptions. The Fifth Circuit’s interpretation could also potentially complicate the government’s burden in proceedings outside the administrative context, such as in False Claims Act (“FCA”) cases based on pharmacy defendants’ alleged failure to appropriately exercise corresponding responsibility. Defendants in CSA-related litigation should thus carefully evaluate whether this decision and its narrow interpretation of key regulations may open the door to new potential defenses in their cases.

Please contact the Goodwin team with any questions related to the CSA, FCA, or other information in this client alert.