A federal judge in the U.S. District Court for the Northern District of California recently vacated several provisions of Endangered Species Act (ESA) regulations, concluding key parts of rules issued in 2019 and revised in 2024 conflict with federal law.
In a March 30 order resolving cross-motions for summary judgment, the court found that four of six challenged regulatory provisions were unlawful, while upholding others and rejecting claims brought under the National Environmental Policy Act (NEPA).
Background
The case stems from regulatory changes finalized in 2019 by the U.S. Fish and Wildlife Service and National Marine Fisheries Service governing implementation of the ESA sections 4 and 7.
Environmental organizations, including the Center for Biological Diversity, the Sierra Club and WildEarth Guardians, challenged those rules, arguing they weakened protections for listed species and violated both the ESA and NEPA.
Following that remand, the agencies issued updated regulations in 2024 that modified some provisions but retained others. Earthjustice, representing the environmental groups, filed a new lawsuit challenging both the 2019 and 2024 rulemakings, arguing the regulations were inconsistent with the ESA and, in part, procedurally deficient.
The case moved forward on cross-motions for summary judgment, with the court finding that the dispute centered on legal issues that could be decided under the Administrative Procedure Act.
Court ruling
Federal defendants asked the court to pause the case or remand it to the agencies, citing a new rulemaking effort they expect to complete in 2026. The court rejected that request, finding a delay was not warranted. Instead, the judge proceeded to rule on the merits, signaling that ongoing regulatory efforts did not justify postponing judicial review of existing rules.
On summary judgment, the court issued a mixed ruling.
The court concluded that four regulatory provisions—primarily affecting ESA Section 7 consultation requirements—were inconsistent with the statute or were adopted arbitrarily and capriciously. At the same time, the court upheld other aspects of the rulemaking, including rejecting claims that the 2024 regulations violated NEPA.
In its analysis, the court emphasized that agencies must act within the limits of the statute and provide reasoned explanations when departing from prior regulatory interpretations. As a remedy, the court vacated several specific provisions and reinstated earlier regulatory language.
The vacated provisions include:
• “Effects of the action” definition: The judge found the revised language narrowed what impacts agencies had to consider, making it easier to overlook indirect and cumulative effects on species. By throwing it out, the court returned to a broader standard that looks at the full range of impacts.[1]
• “Destruction or adverse modification” standard: The court concluded the updated definition allowed agencies to discount incremental harm to critical habitat by evaluating impacts at too large a scale. The reinstated standard requires a closer look at how habitat loss affects a species’ ability to recover.
• Mitigation measures provision: The court determined the regulations allowed agencies to rely on uncertain or non-binding mitigation measures when assessing project impacts. The prior rule restores the requirement that mitigation relied upon in consultation to be sufficiently certain and enforceable.
• Reinitiation of consultation requirements: The court found the agencies acted arbitrarily in removing their obligation to request reinitiation of consultation when new information or changed circumstances arise. The court found that the decision lacked a sufficient explanation and restored the earlier requirement as a safeguard for ongoing federal actions.
ESA standards reaffirmed
According to a press release by the environmental groups, the court found that agencies must rely on the best available science, cannot disregard incremental impacts to habitat, and must adequately justify regulatory changes—particularly when removing or revising long-standing requirements.
Ben Levitan, senior attorney with Earthjustice, called the decision a critical check on regulatory rollbacks.
“Extinction is forever, and today’s ruling strikes down regulations that deprived vulnerable species of a last chance at survival,” Levitan said. “This ruling sends a strong signal to the Trump administration that its pending plans to further weaken the rules will violate the law.”
Joanna Zhang, endangered species advocate with WildEarth Guardians, said the outcome reinforces the law’s long track record.
“For more than 50 years, the Endangered Species Act has been one of the most successful conservation laws we have,” Zhang said. “This victory gives vulnerable species and the ecosystems we all rely on a chance to recover in the face of the climate crisis and relentless pressure from extractive industries.” — Charles Wallace, WLJ contributing editor
