Loper Bright does not impact challenges involving:

• Agency factual or scientific determinations. Courts often defer to agencies on questions of fact or science. Post-Loper Bright, agencies are even more likely to frame disputes as factual in nature, emphasizing technical or scientific issues that invoke agency deference rather than framing the dispute as one turning on the meaning of a particular statutory term. 
• The adequacy of agency reasoning or the soundness of an agency’s decision. These challenges have always been subject to arbitrary-and-capricious review.
• Agency interpretations of ambiguous regulations. These challenges are evaluated using the Kisor framework, under which an agency’s interpretation of its own ambiguous regulation may be entitled to deference if the agency’s interpretation was thoughtful. considered, and not an after-the-fact litigating position.
• Agency decisions that did not invoke Chevron deference. If the agency never invoked Chevron deference, a court reviews de novo, both before and after Loper Bright.
• Agency decisions based on delegated interpretive authority. If Congress directed that a certain term shall be defined by agency regulation, or that the agency’s action be “reasonable” or “appropriate” or similar discretion-conferring words, the court will review the agency’s action only to determine if it’s arbitrary or capricious.
• Agency decisions with constitutional infirmities. Courts always review constitutional challenges de novo.
• Agency decisions with procedural deficiencies. Issues of agency procedure – like whether the agency had to go through notice-and-comment rulemaking – were never Chevron issues to begin with.
• Agency decisions where the agency did not have authority to interpret the statute in question. FERC’s interpretation of an ambiguous provision of the Clean Water Act, for example, would never get deference even in the prior regime.

At bottom, Loper Bright changes the landscape only when an agency is interpreting an ambiguous term in a statute the agency has the power to interpret. There may be other problems with an agency’s action – and we’re here to help you identify and challenge them – but they are not Loper Bright problems. 

Authored by Catherine Stetson, Susan Cook, Sean Marotta, and Danielle Desaulniers Stempel.