A coalition of U.S. states and municipalities has launched legal action against the Environmental Protection Agency in response to the Trump administration's rollback of federal climate emissions rules, initiating what legal observers expect to be a prolonged court battle over environmental regulatory authority.

The lawsuits argue that the EPA's repeal of the emissions standards violated federal administrative law and left states without adequate protections to address climate-related harms. Plaintiffs include multiple Democratic-led states and at least one major city, according to reporting from The Guardian and Axios.

The litigation carries significant constitutional stakes. Axios reports that the cases could prompt the Supreme Court to weigh in on whether federal law preempts state-level climate claims — a legal question that has been building across several jurisdictions. A ruling on preemption could determine whether localities retain the authority to pursue independent climate accountability measures.

The Trump administration has defended its EPA decisions as lawful exercises of executive authority, consistent with its broader deregulatory agenda. Administration supporters argue that the original emissions rules exceeded the agency's statutory mandate and imposed undue economic costs.

Conservative legal commentators have been sharply critical of the lawsuits, characterizing them as an attempt to achieve through litigation what climate advocates have failed to accomplish through legislation. The cases are expected to proceed through lower federal courts before any potential Supreme Court review.