Agencies Rescind “Harm” Definition

On July 14, 2026, the U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS) (collectively, Services) published a final rule to rescind the definition of “harm” from their Endangered Species Act (ESA) implementing regulations (Final Rule). For decades, the Services’ definition of “harm”—which indicated that, under certain circumstances, modifying the habitat of ESA-listed species could result in prohibited “take”—has been the primary means by which the ESA impacts private activities. Following the effective date of the Final Rule on September 14, 2026, many activities that would have been regulated under the former definition may no longer be. For now, it remains unclear how the Services will administer the “take” prohibition of the ESA moving forward, and how federal courts will interpret the same.

Background

Section 9 of the ESA prohibits “take” of endangered species of fish and wildlife. “Take” is defined by ESA section 3 as “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.” By regulation, the Services have defined the term “harm” to include habitat modification under certain circumstances. USFWS’s definition—“an act which actually kills or injures wildlife…[and] may include significant habitat modification where it actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding or sheltering”—was upheld in 1995 by the U.S. Supreme Court in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon (Sweet Home). Relying on the Chevron doctrine (courts should defer to a federal agency’s reasonable interpretation of ambiguous statutes administered by the agency), the majority in Sweet Home determined that USFWS’s definition of “harm” was a reasonable interpretation of Congressional intent. Justice Antonin Scalia, along with Chief Justice Rehnquist and Justice Thomas, dissented from the majority. In his dissent, Justice Scalia indicated that only “affirmative conduct intentionally directed against a particular animal or animals” constitutes “take” under the ESA.

In 2024, the U.S. Supreme Court issued a decision in Loper Bright Enterprises v. Raimondo (Loper Bright), which overturned Chevron deference and held that it is the job of federal courts rather than federal agencies to determine the best meaning of ambiguous statutes. Following the Loper Bright decision, the Services published a proposed rule to rescind their regulatory definitions of “harm” (Proposed Rule), stating that the agencies had determined that their respective definitions of “harm” did not constitute the single, best meaning of the ESA, and that Justice Scalia’s interpretation of “take” as set forth in his Sweet Home dissent represented the best interpretation.

Final Rule

In their responses to public comments set forth in the preamble to the Final Rule, the Services acknowledged that private entities seeking permits under section 10 of the ESA will no longer need to account for the impact to a species’ habitat or explain how habitat modification or degradation will be minimized or mitigated, and that incidental take permits will no longer consider effects of the proposed action or contain terms and conditions requiring permittees to take habitat modification or degradation into account. The Services indicated, however, that permits issued pursuant to ESA section 10 and incidental take statements issued pursuant to ESA section 7 prior to the effective date of the Final Rule will not be affected.

What’s Next

While the particulars of how the Services will implement the “take” prohibition are uncertain following their rescission of the “harm” definition and adoption of Justice Scalia’s interpretation of what constitutes “take,” there is a virtual certainty that the issue will be litigated in various ways and a strong potential that future presidential administrations could endeavor to re-promulgate the original “harm” definition or adopt an entirely new definition.

As of the writing of this post, at least six separate lawsuits have been filed challenging the sufficiency of the rulemaking. In addition to lawsuits challenging the sufficiency of the rulemaking process associated with the Final Rule, it is likely that project-specific challenges will be brought seeking to have courts weigh in on whether a given activity or impact meets the statutory definition of “take.” Pursuant to the Supreme Court’s directive in Loper Bright, each federal court will determine whether the activity or impact meets the definition of “take,” which raises the potential that different courts looking at similar fact patterns may come to different conclusions.

Absent Congressional action or a definitive ruling by the Supreme Court, it is possible that the issue of “take” under the ESA may be unsettled for quite some time.