California's Clean Air Act waivers: from the 2019 revocation to the 2025 Congressional Review Act resolutions

Case

California has received more than 100 Clean Air Act waivers since 1967, and one was revoked before 2025: its greenhouse-gas and zero-emission-vehicle waiver, in Trump's first term, restored under Biden. In May-June 2025 Congress used the Congressional Review Act to overturn three more waivers and Trump signed the resolutions, although GAO and the Senate parliamentarian said the law does not apply to waivers. California and ten states sued on June 12, 2025.

Background: section 209 waivers
Since 1967 California has applied for and received more than 100 Clean Air Act waivers to set its own vehicle standards. In that time a waiver was denied once (2008) and revoked once, in the first Trump administration; the revoked waiver was reinstated under Biden.
Before 2025, EPA treated waivers as adjudicatory orders that could be denied only for reasons listed in the statute, not as rules. DWT notes the Congressional Review Act had never been used to overturn an EPA waiver.

First term: the 2019 revocation
On Sept. 27, 2019, the SAFE Vehicles Rule Part 1 revoked California's 2013 waiver for greenhouse-gas and zero-emission-vehicle standards and barred other states from adopting California's greenhouse-gas standards. NHTSA claimed federal fuel-economy law preempted the standards, and EPA claimed a new reading of "compelling and extraordinary conditions."
States, localities and environmental groups challenged the rule in the D.C. Circuit on Oct. 28, 2019 (Union of Concerned Scientists v. NHTSA). The Harvard paper cited here was written in March 2021 and does not report how the case ended.

Second term: the 2025 resolutions
Congress passed three joint resolutions under the Congressional Review Act nullifying California waivers for Advanced Clean Cars II (phasing out new gas-powered cars by 2035), Advanced Clean Trucks, and the Omnibus Low NOx rule. The Senate vote was May 22, 2025; the House vote date and vote counts were not found for this entry.
Trump signed the resolutions on June 12, 2025 per CalMatters and EDF; Smart Cities Dive gives June 13. He said, "We officially rescue the U.S. auto industry from destruction by terminating California's electric vehicle mandate," and called the rules "fully and expressly preempted by the Clean Air Act."
The Government Accountability Office and the Senate parliamentarian had both opined that EPA waivers are not rules subject to the Congressional Review Act.
California Attorney General Rob Bonta and ten other states (Colorado, Delaware, Massachusetts, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont and Washington) sued Trump and EPA Administrator Lee Zeldin on June 12, 2025 in the Northern District of California, arguing the waivers are not subject to the Act and that the revocation violates several provisions of the Constitution.
Gov. Gavin Newsom said, "Trump's all-out assault on California continues – and this time he's destroying our clean air." Rep. Doug LaMalfa said the mandates "would have made it harder and more expensive for Americans to buy the cars they need."

Perspectives

Official position — President Trump and congressional supporters
California's rules were extreme mandates "fully and expressly preempted by the Clean Air Act," and ending them rescues the U.S. auto industry and keeps cars affordable and available. Supporters such as Rep. Doug LaMalfa said the mandates would have made it harder and more expensive for Americans to buy the cars they need.

Legal view — California and ten states; GAO and the Senate parliamentarian (as reported)
EPA waivers are adjudicatory orders, not rules, so the Congressional Review Act cannot be used to nullify them. California argues the revocation also violates several provisions of the Constitution. GAO and the Senate parliamentarian had earlier concluded the Act does not reach waivers.

Research notes
Open leads: (1) House vote date and tallies for the three resolutions; the resolution numbers. (2) Status of California v. United States in the Northern District of California as of fall 2026, and any ruling on whether the Congressional Review Act applies to waivers. (3) How the 2019 SAFE Part 1 litigation ended and the date the waiver was restored under Biden (DWT says only that it was reinstated). (4) Rep. Neguse's exchange with the witness identified by The Author as Rep. John Joyce concerns state waivers versus polluter exemptions; the hearing is unidentified, and whether it concerned these resolutions is not established. (5) Signing date: June 12 (CalMatters, EDF) vs June 13 (Smart Cities Dive).

Note
Supporters say the waivers imposed extreme mandates preempted by federal law, while California, GAO and the Senate parliamentarian say Congress had no power to nullify them under the Congressional Review Act.

Sources
[1] Davis Wright Tremaine — California leads 10 others suing over revocation of vehicle emission waivers (https://www.dwt.com/blogs/energy--environmental-law-blog/2025/06/california-epa-clean-air-emission-waivers-lawsuit) · 2025-06
[2] CalMatters — California sues Trump for blocking its clean-air rules for cars, trucks (https://calmatters.org/environment/2025/06/california-sues-trump-blocking-clean-air-rules-cars/) · 2025-06-12
[3] Smart Cities Dive — Trump ends California vehicle emissions waivers (https://www.smartcitiesdive.com/news/california-vehicle-emissions-waiver-rescinded-clean-air-act/749001/) · 2025-06
[4] Environmental Defense Fund — President signs Congressional Review Act resolutions attacking state clean vehicle standards (https://www.edf.org/media/president-signs-congressional-review-act-resolutions-attacking-state-clean-vehicle-standards) · 2025-06-12
[5] Harvard Environmental & Energy Law Program — SAFE Rule Part 1 (Lia Cattaneo, Mar. 2021) (https://eelp.law.harvard.edu/wp-content/uploads/2025/01/Lia-Cattaneo-SAFE-Rule-Part-1_final_singlespaced.pdf) · 2021-03-26

Connections

Same context — Environmental deregulation under EPA Administrator Lee Zeldin
The 2025 waiver revocations are part of the broader rollback of vehicle and climate rules.

Related — EPA's "electronic mailbox" for Clean Air Act exemptions and the presidential proclamations (2025-2026)
California's higher-standard waivers were nullified while industry-requested exemptions from air-toxics rules were granted, the contrast Rep. Neguse put to a witness.

Same context — Oil, gas and the EPA: a timeline of Trump-era leadership, rollbacks and industry requests (2014-2026)
The 2019 revocation and 2025 resolutions are entries in the timeline.