The harm of redefining ‘harm’

Last year, The Wildlife Society submitted comments critical of the U.S. Fish and Wildlife Service’s proposal to rescind the regulatory definition of “harm” under the Endangered Species Act. On September 14, that rule is set to take effect. While framed as an effort to limit agency authority after the Supreme Court’s decision overturning the Chevron deference, the rule raises a fundamental question: Can an agency claim it lacks authority to define a statutory term while simultaneously advancing a new interpretation of that same term?

The Chevron deference was a Supreme Court legal doctrine that directed courts to defer to a federal agency’s reasonable interpretation of an ambiguous statute. The Supreme Court overturned this doctrine in the case Loper Bright Enterprises v. Raimondo (2024).

As identified in TWS’ comments on USFWS’ proposal, the rule does more than remove a regulatory definition. In the accompanying narrative provided by the USFWS and promoted by agency officials, the now finalized rule implies that habitat modification no longer constitutes “harm” under the ESA. The agency is effectively replacing one interpretation of “harm” with another. That creates an obvious tension. If agencies lack authority to define ambiguous statutory terms, they should also lack authority to substitute a new definition for an old one.

As TWS notes in our comments, when the Supreme Court overturned the Chevron deference, the Court did not overturn prior precedents and explicitly stated that earlier decisions relying on Chevron remain intact. To that point, the federal Supreme Court has already spoken on the definition of “harm.” In Babbitt v. Sweet Home (1995), the Court held that habitat modification can constitute “harm” under the ESA and found the agency’s definition consistent with the statute’s text, structure and legislative history. Unless Congress amends the ESA or the Supreme Court revisits Babbitt v. Sweet Home, the governing interpretation of “harm” remains unchanged.

Similarly, TWS’ position remains unchanged. If agencies wish to remove regulations post-Chevron deference, they should also acknowledge that existing Supreme Court precedent continues to govern the meaning of the law and that Congress retains ultimate authority to clarify ambiguous statutory terms. Any suggestion beyond that effectively rewrites the law without action from either Congress or the Court. It also mires the law in uncertainty and conflict where none should exist.

Unfortunately, this legal contradiction could have real-world consequences. Habitat loss remains one of the leading causes of species decline, and uncertainty surrounding the meaning of “harm” could complicate implementation and enforcement of ESA.

If you want to take action, contact the branch of government constitutionally responsible for creating and amending federal law. Contact your congressional representatives.

Read TWS’ comments on the ESA regulatory definition of harm here.