Lummis, Cruz File Amicus Brief Backing Trump Administration’s Push to Repeal Endangerment Finding

April 15, 2026

Washington, D.C. - Senator Cynthia Lummis (R-WY) and Senator Ted Cruz (R-TX) have filed an amicus brief in support of the Trump administration's repeal of the greenhouse gas endangerment finding, arguing that the Environmental Protection Agency is operating without the congressional authorization needed to enforce these types of regulations.

Senator Lummis currently serves as Chairman of the Subcommittee on Clean Air, Climate, and Nuclear Innovation and Safety for the Senate Committee on Environment and Public Works. Senator Cruz serves as Chairman of the Subcommittee on Federal Courts, Oversight, Agency Action and Federal Rights for the Senate Committee on the Judiciary.

Excerpts from the amicus brief are included below; the full text can be reviewed here.

Senators Ted Cruz and Cynthia Lummis respectfully move this Court for leave to file the attached proposed brief as amici curiae in this matter. In support of their Motion, amici state as follows:

1. Amici Curiae are Senators Ted Cruz and Cynthia Lummis, who represent the States of Texas and Wyoming, respectively, in the United States Senate. Senator Cruz serves as Chairman of the Subcommittee on Federal Courts, Oversight, Agency Action and Federal Rights for the Senate Committee on the Judiciary. Senator Lummis serves as Chairman of the Subcommittee on Clean Air, Climate, and Nuclear Innovation and Safety for the Senate Committee on Environment & Public Works. Amici's respective interests overlap perfectly here.

2. Namely, both have a strong interest in judicial interpretations that preserve the legislative powers that Article I of the Constitution vests exclusively in Congress. Amici share an interest in ensuring that the judiciary serves as an appropriate check on the executive branch and vigilantly safeguards the Constitution's separation of powers. In addition, amici have an interest in ensuring that executive agencies-- like the EPA--exercise only the authority Congress delegated to them, meaning that Congress retains all federal legislative power. When an executive agency issues regulations with vast economic and political significance, the courts must invoke the major questions doctrine to protect the Constitution's separation of powers.

3. As members of the U.S. Senate, amici possess a unique interest in, and perspective on, the EPA's reliance on the major question doctrine to repeal its 2009 Endangerment Finding and corresponding regulations concerning greenhouse gas emissions standards for vehicles and engines. Amici respectfully submit this amici curiae brief pursuant to these interests and their unique perspective as U.S. Senators.

4. Counsel for amici contacted counsel for the parties in No. 26- 1037 on April 6, 2026, to obtain their positions on the Motion. Counsel for amici contacted counsel for the parties in the consolidated cases on April 8, 2026, to obtain their positions on the Motion. Respondents consent to the Motion. Petitioners in No. 26-1037 consent to the Motion provided that the brief complies with Rule 29. Petitioners in No. 26-1043, Missouri Coalition for the Environment and Metropolitan Congregations United, take no position. Petitioner in No. 26-1051, Service Employees International Union, takes no position. The State and local government Petitioners in No. 26-1061 take no position on the Motion. The remaining Petitioners provided no position before the filing of this Motion.

5. The proposed brief is desirable and relevant to the disposition of the case. The brief describes how the major questions doctrine plays a central role in preserving separation of powers by ensuring that questions of economic and political significance are resolved by Congress, not administrative agencies. And it explains how the EPA's invocation of the major questions doctrine in repealing the 2009 Endangerment Finding and greenhouse gas vehicle standards preserves Congress's lawmaking authority. The Court must uphold that necessary conclusion to ensure that Congress maintains its role as supreme lawmaker in the face of Executive overreach.

6. Pursuant to Circuit Rule 29(d), counsel for amici state that one amicus brief was lodged on March 13, 2026, and again on March 31, 2026, by a party that is also appearing as an intervenor (John Worthington). Another amicus brief was lodged on March 19, 2026, by Government Accountability & Oversight and Government Oversight & Education. Amici were not notified of either brief, which were filed nearly a month before amici are seeking leave, and therefore did not have an opportunity to contribute to them. Additionally, neither brief analyzes the major questions doctrine and its applicability to the EPA's 2009 Endangerment Finding and greenhouse gas vehicle emission standards. Amici's unique perspective as members of Congress on the applicability of the major questions doctrine to this case further renders a separate brief necessary and desirable.

7. Accordingly, amici respectfully request that the Court grant them leave to file the proposed brief as amici curiae.

###