A coalition of 24 states, led by Massachusetts, California, New York, and Connecticut, filed a lawsuit against the Trump administration on Thursday. They accuse the Environmental Protection Agency (EPA) of illegally rescinding the 'endangerment finding' - the 2009 scientific assessment declaring carbon dioxide and other greenhouse gases a threat to public health and welfare. This finding formed the legal bedrock for regulating emissions from vehicles, power plants, and industrial sources.

The lawsuit seeks to reinstate the finding, forcing the EPA to retain authority over greenhouse gas regulation. It also targets a separate EPA move repealing vehicle emission limits, which account for over a third of US climate pollution. 'The endangerment finding is critical to protect our families,' stated Massachusetts AG Andrea Joy Campbell. The states argue the EPA offered no new science or legal precedent to justify abandoning the finding, calling it a 'blatant violation of the law.' This case is expected to be consolidated with an earlier environmental group lawsuit, creating one of the largest legal challenges to the Trump administration's dismantling of climate policy.

Legal experts see this as a potential path to the Supreme Court, aiming to overturn the 2007 Massachusetts v. EPA ruling that greenhouse gases are pollutants under the Clean Air Act.