Although the U.S. Supreme Court’s 2024 decision in Loper Bright Enters. v. Raimondo, 603 U.S. 369 overturned the Chevron deference doctrine, deference to an agency’s interpretation of its own regulations under Auer v. Robbins, 519 U.S. 452 (1997), was left untouched. In 2019, the Supreme Court refined the Auer deference doctrine by adding a multifactor test to determine whether deference is owed to an agency’s interpretation of its own regulation. Kisor v. Wilkie, 588 U.S. 558.
In Cascadia, plaintiffs challenged the U.S. Bureau of Land Management’s (BLM) approval of a land management action authorizing a logging project on federally owned land (the BWE Project). Plaintiffs argued the BWE Project violates an earlier BLM resource management plan that protects a species of seabird. Plaintiffs claimed that BLM’s interpretation of the term “modifying nesting habitat” in the earlier plan was too narrow because it excluded indirect environmental impacts. The district court granted summary judgment to BLM.
The Ninth Circuit affirmed. The court concluded that, under Kisor, a court may defer to an agency’s interpretation of its own regulation (here, a resource management plan) if three criteria are met: “(1) the regulation is ‘genuinely ambiguous,’ (2) the [agency’s] interpretation is ‘reasonable,’ and (3) the interpretation is entitled to ‘controlling weight.’ ” Cascadia Wildlands, 2025 WL 2460946, at *16 (quoting Kisor, 588 U.S. at 574–79). The court further held that the final factor requires courts to consider “the character and context” of the agency’s interpretation, i.e., “whether the interpretation (1) constitutes the agency’s ‘official position . . . (2) implicates the agency’s ‘substantive expertise,’ and (3) reflects the agency’s ‘fair and considered judgment.’ ” Id. at *19. The court found that under the Kisor test, BLM’s narrow interpretation was a reasonable interpretation of a genuinely ambiguous term, entitled to controlling weight and thus due deference.
