Whether the Attorney General's Interpretive Rule was entitled to controlling deference as an interpretation of the Attorney General's own regulation under Auer v. Robbins.
Holding
No. The Rule did not interpret an independent agency regulation in a manner warranting Auer deference; it effectively interpreted the CSA itself.
Reasoning
The relevant regulation requires a controlled-substance prescription to be issued for a "legitimate medical purpose" by a practitioner acting in the usual course of professional practice. But that language substantially repeats terms used in the CSA. The regulation does not answer the central question in the case: who has authority to decide whether physician-assisted suicide is a legitimate medical practice.
An agency does not gain special authority to resolve a statutory ambiguity simply by restating statutory language in a regulation. Because the Interpretive Rule's real subject was the meaning and reach of the CSA, rather than a distinct regulatory standard developed through the Attorney General's expertise, Auer deference did not apply.
The regulation also predated the 1984 CSA amendments on which the Government principally relied for the Attorney General's registration authority. The later Interpretive Rule therefore could not plausibly be treated as an explanation of the Attorney General's original regulatory intent.