Case: Commonwealth of Massachusetts v. United States Fish And Wildlife Service
4:26-cv-10072 | U.S. District Court for the Northern District of California
Filed Date: Sept. 9, 2026
Case Ongoing
Clearinghouse coding complete
Case Summary
This case challenges two United States Fish & Wildlife Service (FWS) rules finalized on July 21, 2026 – the 4(d) Rule and the Habitat Exclusion Rule – that harm State plaintiffs by undermining and weakening key requirements of the Federal Endangered Species Act (ESA). The 4(d) Rule rescinded FWS's prior regulation–an automatic "blanket rule" extending all ESA Section 9 "take" prohibitions to newly listed threatened species. The Habitat Exclusion Rule created a new process for excluding areas of critical habitat from designation, which could eliminate protections for those areas under Section 7 and other provisions of the ESA.
On September 9, 2026, plaintiffs, twenty states plus the District of Columbia, filed this lawsuit in the U.S. District Court for the Northern District of California against defendants, FWS, the Director of FWS, the Secretary of the U.S. Department of the Interior, and the Principal Deputy for Fish and Wildlife and Parks. Represented by Attorneys General for each state and the district, the plaintiffs alleged five causes of action.
First, plaintiffs alleged the 4(d) Rule violated the ESA's plain language, structure, and purpose and the Administrative Procedure Act (APA) by exceeding FWS's jurisdiction, authority, and discretion under the ESA. Second, plaintiffs alleged the 4(d) Rule violated the APA because FWS acted in a manner that was arbitrary, capricious, and an abuse of power by providing no reasoned basis for abandoning its longstanding policy and practice of providing default Section 9 protections to all newly listed threatened species. Third, plaintiffs alleged the Habitat Exclusion Rule violated the ESA because it was contrary to the Section 4 critical habitat designation requirements, the Section 7 consultation requirements, and the ESA's conservation purposes and mandate. Plaintiffs further alleged the FWS violated the APA by acting in a manner that was contrary to law, as an abuse of discretion, and in excess of FWS's statutory jurisdiction and authority. Fourth, plaintiffs alleged the FWS violated the APA by failing to adequately consider and explain several aspects of the Habitat Exclusion Rule that prioritize economic factors and critical habitat exclusions over designation of critical habitat and conservation of endangered and threatened species, and thus acted in a manner that was arbitrary, capricious, and an abuse of discretion. Fifth, plaintiffs alleged Rule 4(d) and the Habitat Exclusion Rules violated the National Environmental Policy Act (NEPA) and APA. FWS's failure to comply with NEPA's requirements to take a "hard look" at the environmental impacts of the Rules in an environmental impact statement or an environmental assessment violated APA by being a decision that was arbitrary, capricious, and an abuse of discretion.
The plaintiffs sought a declaratory judgment that FWS violated the ESA, NEPA and APA, and an order vacating the Final Rules, costs, and additional relief as the court deems just and proper. The case was initially assigned to Magistrate Judge Ajay S. Krishnan and subsequently reassigned to District Judge Jon S. Tigar.
A joint case management statement by the parties is due by January 19, 2027, and an initial case management conference is set for January 26, 2027.
The case is ongoing.
Summary Authors
Raquel Winer (9/29/2026)
People
For PACER's information on parties and their attorneys, see: https://www.courtlistener.com/docket/74766354/parties/commonwealth-of-massachusetts-v-united-states-fish-and-wildlife-service/
Aguilera, Susana (California)
Arizona, State of (California)
Breidenbach, Christopher G. (California)
Brinkman, Joanna (California)
California, State of (California)
Arizona, State of (California)
Breidenbach, Christopher G. (California)
California, State of (California)
Colorado, State of (California)
Columbia, District of (California)
Connecticut, State of (California)
Delaware, State of (California)
Garrahan, Paul Andrew (California)
Harris, Elizabeth Marie (California)
Illinois, State of (California)
Lewis, Heather Mudford (California)
Loda, Jennifer Lynn (California)
Maryland, State of (California)
Massachusetts, Commonwealth of (California)
Michigan, State of (California)
Minnesota, State of (California)
Mueller, Tara Lynn (California)
Rios-Keating, Catherine (California)
Smith, Maggie Baker (California)
Vermont, State of (California)
Virginia, Commonwealth of (California)
Washington, State of (California)
Documents in the Clearinghouse
Docket
See docket on RECAP: https://www.courtlistener.com/docket/74766354/commonwealth-of-massachusetts-v-united-states-fish-and-wildlife-service/
Last updated Oct. 4, 2026, 3:05 a.m.
Docket for: Commonwealth of Massachusetts v. United States Fish And Wildlife Service
Case Details
State / Territory:
Case Type(s):
Special Collection(s):
Trump Administration 2.0: Challenges to the Government
Key Dates
Filing Date: Sept. 9, 2026
Case Ongoing: Yes
Plaintiffs
Plaintiff Description:
20 States plus the District of Columbia
Plaintiff Type(s):
Public Interest Lawyer: No
Filed Pro Se: No
Class Action Sought: No
Class Action Outcome: Not sought
Defendants
Federal
U.S. Department of the Interior
U.S. Department of the Interior
United States Fish and Wildlife Service
Defendant Type(s):
Facility Type(s):
Case Details
Causes of Action:
Administrative Procedure Act, 5 U.S.C. §§ 551 et seq.
Endangered Species Act, 16 U.S.C. § 1531 et seq.
National Environmental Protection Act, 42 U.S.C. §§ 4321–4370f
Other Dockets:
Northern District of California 4:26-cv-10072
Available Documents:
Outcome
Prevailing Party: None Yet / None
Relief Sought:
Relief Granted:
Source of Relief:
Issues
Environmental Justice and Resources:
Environmental Impact Statements
Case Summary of Commonwealth of Massachusetts v. United States Fish And Wildlife Service, Civil Rights Litig. Clearinghouse, https://clearinghouse.net/case/48439/ (last updated 9/29/2026).