When a court reviews an agency’s regulation and finds it to be partially invalid, the court must determine the proper remedy. Should the court vacate the entire regulation, issue a remand to the agency without vacatur, or sever the offending portion and allow the lawful remainder to take effect? The issue of regulatory severability is increasingly important in administrative law after Corner Post, Inc. v. Board of Governors of the Federal Reserve System effectively eliminated the statute of limitations for APA challenges and Loper Bright Enterprises v. Raimondo ended judicial deference to agency interpretations of law.

Few circuit courts or scholars have considered regulatory severability as a concept distinct from statutory severability. Yet as this Note argues, there is good reason for a difference to exist: While judicial review of statutes is governed by constitutional first principles, judicial review of regulations is governed by statutes. Indeed, in early administrative law cases, the Supreme Court looked to statutory review provisions to determine what remedies a court could provide for a partially invalid agency action. This Note advances a novel interpretation of the APA’s judicial review provision as instructing courts to sever regulations where possible.

The Supreme Court has repeatedly described the APA as the “fundamental charter of the administrative state.” And in landmark cases from Darby v. Cisneros to Loper Bright, the Court has proven willing to overturn settled practices in the circuit courts when those practices fail to align with the APA’s text. Obeying the APA’s preference for severability is a critical next step in the wake of decisions rendering more agency actions more vulnerable to judicial second-guessing.

* J.D., Stanford Law School, 2025. I am grateful to Mila Sohoni for advising and encouraging this project; to Michael McConnell and the Bradley Law Student Fellowship for providing support and feedback; and to Alex Mechanick, Paloma O’Connor, Paige Singer, and Taylor Barker for invaluable comments and conversations. Thanks to the editors of the Stanford Law Review, in particular Rachel Blatt and Damian Richardson, for their help throughout the revision process.