Endangered Species Law & Policy

On August 25, 2026, the United States Court of Appeals for the D.C. Circuit issued a notable Endangered Species Act (ESA) decision in Center for Biological Diversity v. EPA, No. 25-1005. The Center for Biological Diversity (CBD) had filed a petition for review challenging a final rule published by the Environmental Protection Agency (EPA), which retained the existing national ambient air quality standard for nitrogen oxides and particulate matter and revised the standard for sulfur oxides. CBD argued that EPA violated the ESA by concluding that the challenged air quality rule ...

On December, 10, 2018, the United States Supreme Court granted a petition for writ of certiorari in Kisor  v. Wilkie (No. 18-15), which raises the issue of whether Auer deference should be overruled.  Auer deference (also known as Seminole Rock deference) requires courts to defer to an agency's reasonable interpretation of its own ambiguous regulations.  Auer deference is similar to Chevron deference, which requires courts to defer to an agency's reasonable interpretation of ambiguous statutes.  As this blog has noted, agency deference has been in the spotlight recently ...