Federal Agencies Rescind Endangered Species Act Definition of “Harm,” Narrowing the Scope of Prohibited Activity Affecting Wildlife

The U.S. Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) have issued a final rule rescinding the regulatory definition of “harm” under the Endangered Species Act (ESA). The change is significant because the longstanding definition provided that prohibited “harm” could include significant habitat modification or degradation that kills or injures protected wildlife by impairing essential behavioral patterns, such as breeding, feeding, sheltering, spawning, rearing, or migrating. After the rule becomes effective, the agencies will instead apply the ESA’s statutory definition of “take” without a separate definition of “harm.”

The Agencies’ Revised Interpretation of “Take”

Section 9 of the ESA generally prohibits the “take” of endangered wildlife. The statute defines “take” to mean “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect,” or attempting to engage in such conduct. The agencies’ prior regulations interpreted “harm” to reach certain indirect injuries caused by habitat modification, and that interpretation was upheld by the Supreme Court in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon in 1995.

In the final rule, however, FWS and NMFS conclude that the prior definition does not reflect the “single, best meaning” of the ESA following the Supreme Court’s 2024 decision in Loper Bright Enterprises v. Raimondo. The agencies adopt the reasoning of Justice Scalia’s dissent in Sweet Home, under which “take” generally requires affirmative conduct directed immediately and intentionally against particular animals, rather than conduct that indirectly and accidentally injures a wildlife population. The agencies determined that no replacement definition is necessary.

Implications for Habitat Modification

The final rule may materially narrow the circumstances in which land development, resource extraction, infrastructure construction, and similar activities require incidental take authorization solely because they modify habitat.

Most notably, the agencies state that parties seeking incidental take permits under the ESA will no longer be required to address, minimize, or mitigate habitat modification or degradation that does not independently constitute statutory “take.” The agencies also indicate that the they will no longer consider habitat effects or impose habitat-related permit conditions on that basis alone.

The rule applies prospectively, and previously issued incidental take permits will not be required to be reevaluated because of the rescission. Existing conservation agreements and habitat management plans likewise will not automatically be invalidated.

What Comes Next

The rule represents a substantial change to decades of ESA implementation and is likely to face judicial challenges. Until courts and the agencies provide additional guidance, the boundaries of prohibited “harm” are likely to remain a significant project-specific issue. The rule will become effective 60 days after publication in the Federal Register.

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