SF, Santa Clara Join Coalition Suing EPA Over Rescinded Climate Finding

Every mile driven on Bay Area freeways now sits at the center of a federal courtroom battle, as San Francisco City Attorney David Chiu and Santa Clara County Counsel Tony LoPresti announced last Thursday that their jurisdictions had joined a sweeping multistate petition challenging the Environmental Protection Agency's decision to rescind the 2009 Endangerment Finding, the legal foundation the federal government has used to regulate greenhouse gas emissions from motor vehicles.

The petition, filed in the United States Court of Appeals for the District of Columbia Circuit under the case caption Commonwealth of Massachusetts, et al. v. United States Environmental Protection Agency, et al., seeks to reinstate federal standards limiting climate pollution from vehicles. The Endangerment Finding itself is the EPA's formal determination that greenhouse gas emissions from motor vehicles contribute to air pollution that fuels climate change and endangers public health. Without it, the Clean Air Act's authority to cap vehicle emissions loses its underpinning.

San Francisco and Santa Clara County joined a coalition that includes 25 attorneys general, the Governor of Pennsylvania, and ten cities and counties. The effort is led by the attorneys general of Massachusetts, California, New York, and Connecticut, placing California's top law enforcement officer among the four states steering the litigation.

The scale of the coalition reflects how broadly local governments view the stakes. San Francisco's participation adds a jurisdiction that has long embedded climate obligations into its planning and infrastructure decisions, while Santa Clara County's involvement underscores the regional reach of the challenge across the Bay Area.

The press release announcing the action did not name outside counsel representing San Francisco or Santa Clara County in the D.C. Circuit case, nor did it list the 25 attorneys general individually or identify all ten of the additional cities and counties in the coalition. The full petition is available through the San Francisco City Attorney's office, which can be reached at (415) 554-4700 or cityattorney@sfcityatty.org.

The EPA challenge is separate from another lawsuit Chiu and LoPresti announced in December 2025, in which San Francisco and Santa Clara County joined a coalition challenging HUD restrictions on its Continuum of Care homelessness funding program. That case, filed in U.S. District Court in Rhode Island, carried projections that the restrictions could push more than 170,000 people nationwide into homelessness. The two cases share plaintiffs but proceed in different courts on entirely different legal questions.