The Endangered Species Act's 'Harm' Definition Is Rescinded: What Changes in 2026

For more than four decades, federal wildlife rules said that destroying habitat could count as "harming" an endangered species. A final rule published on July 14, 2026 removed that definition. Here is what changed, what did not, and what landowners, developers and conservation groups should watch.

Take, harm and habitat

Section 9 of the Endangered Species Act makes it unlawful to "take" an endangered species of fish or wildlife (16 U.S.C. § 1538). The statute defines "take" as to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect, or to attempt any of those acts (16 U.S.C. § 1532(19)). Congress did not define "harm." In 1981 the U.S. Fish and Wildlife Service (FWS) adopted a regulation defining harm as an act that actually kills or injures wildlife, including significant habitat modification or degradation that kills or injures wildlife by significantly impairing essential behavioral patterns such as breeding, feeding or sheltering. The National Marine Fisheries Service (NMFS) adopted a similar definition in 1999.

In Babbitt v. Sweet Home Chapter of Communities for a Great Oregon (1995), the Supreme Court upheld the FWS definition, deferring to the agency's reading of the statute. Our general overview of wildlife protection laws and endangered species explains how listings and permits work.

What the 2026 rule does

After proposing the change in 2025, FWS and NMFS published a final rule on July 14, 2026 that removes the regulatory definition of harm from the Code of Federal Regulations. The Federal Register version states that the rule is effective September 14, 2026; some secondary summaries have cited a different date, so the official text should be used. The agencies concluded that the statutory definition of take is comprehensive and that a replacement definition is unnecessary. In their view, the prohibition reaches direct actions against protected animals, and significant habitat impacts alone will no longer be treated as harm under the regulations.

The rule is prospective. According to the agencies, permits and incidental take statements finalized before the effective date will not have to be re-evaluated. Even so, private parties could still face citizen suits arguing that particular habitat destruction is a take under the statute itself, because courts interpret the statute independently.

Why Loper Bright matters

The Sweet Home decision relied on the framework of Chevron deference, under which courts accepted reasonable agency interpretations of ambiguous statutes. In Loper Bright Enterprises v. Raimondo (2024), the Supreme Court overruled Chevron and held that courts must exercise independent judgment about what a statute means. The agencies cited that change in concluding that the old definition did not reflect the single best reading of the statute. For a practitioner's view of how the end of Chevron affects lawsuits against federal agencies more generally, see this analysis of Loper Bright and the end of Chevron deference.

The legal challenge and what to watch

On July 14, 2026, Earthjustice and several conservation organizations filed suit in the U.S. District Court for the Western District of Washington challenging the rescission. Courts will now decide, without deference to the agencies, what "harm" means in the statute. Possible outcomes range from upholding the rescission to reading habitat modification back into the statute.

Lawsuits that try to make an agency act, rather than challenging a rule it adopted, follow different rules. Under the Supreme Court's decision in Norton v. Southern Utah Wilderness Alliance (2004), a court can compel only a discrete agency action that the agency is legally required to take. This explainer on Norton v. SUWA and the discrete-agency-action rule covers that limit.

Landowners and businesses should continue to evaluate projects carefully, especially where state wildlife laws or other federal statutes also apply. Owners of unusual animals should also review state rules discussed in our guide to exotic animal ownership, and farms can find basics in livestock and agricultural animal law.

Frequently Asked Questions

Does this mean habitat destruction is now legal?

Not necessarily. The regulatory definition is gone, but the statute still prohibits take, other laws may apply, and courts may interpret 'harm' in the statute to include some habitat impacts. Litigation is pending.

When does the rule take effect?

The Federal Register text states September 14, 2026.

Are existing incidental take permits affected?

The agencies state that permits and incidental take statements finalized before the effective date do not need to be re-evaluated under the rule.