Final Rescission Of "Harm" Definition Arrives At OIRA

On April 3, 2026, the final rescission of the U.S. Fish & Wildlife Service and National Marine Fisheries Service (together, Services) definitions of the term “harm” from their respective Endangered Species Act (ESA) implementing regulations arrived at the Office of Information and Regulatory Affairs (OIRA) for E.O. 12866 review. E.O. 12866 requires federal agencies submit “significant” proposals to OIRA prior to issuance in order to ensure, among other things, that such proposals analyze costs and benefits, and avoid conflicting policies. There is no deadline by which OIRA must complete its review. 

ESA section 9 prohibits “take” of species listed as endangered. “Take” is defined by section 3 of the ESA as to “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to engage in any such conduct” and applies to public and private activities alike. By regulation, the Services have long defined the term “harm” to include significant modification or degradation of a species’ habitat, where such modification or degradation of habitat results in actual death or injury to that species, including through impairing essential behavioral patterns, such as breeding, feeding, or sheltering.

The U.S. Fish & Wildlife Service’s definition of “harm” was upheld by the U.S. Supreme Court in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon on the basis of Chevron deference—a doctrine that required federal courts to defer to an agency’s reasonable interpretation of ambiguous statutes administered by that agency. In 2024, the Supreme Court issued its decision in Loper Bright Enterprises v. Raimondo (Loper Bright), in which the Court overturned Chevron deference and explained that federal courts must decide whether the relevant statute authorizes a challenged agency action. When the Services  published their proposed rescission of their definitions of “harm,” the agencies indicated that, following the Supreme Court’s decision in Loper Bright, the Services have concluded that their definitions of “harm” do not match the single, best meaning of the term “harm” in section 3 of the ESA.

In the preamble to the proposed rescission of the regulatory definitions of “harm,” the Services indicated they do not intend to promulgate replacement definitions.

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