**States Sue EPA Over Greenhouse Gas Emissions Regulation Rollback** A group of 20 states, led by California, Massachusetts, Connecticut, and New York, has filed a lawsuit against the US Environmental Protection Agency (EPA) for relinquishing its role as a greenhouse gas emissions regulator. According to *The New York Times*, the lawsuit specifically argues that the EPA's decision to rescind a 2009 study was illegal. This study, known as the "Endangerment Finding," determined that greenhouse gases are hazardous to public health and was a key justification for the EPA's ability to regulate emissions. The EPA's decision to rescind the finding, made during the Trump administration, effectively nullified the agency's evidence for emissions standards and other regulations aimed at reducing greenhouse gas emissions from the automotive, coal, and oil industries. The Trump administration framed the rollback as a cost-saving measure, but it also significantly impaired the government's ability to combat climate change. Greenhouse gases, including carbon dioxide, methane, and nitrous oxide, accumulate in the atmosphere, contributing to global warming and disrupting weather patterns, ultimately posing a risk to public health. The lawsuit was filed in the US Court of Appeals for the District of Columbia and may eventually be combined with an existing lawsuit from environmental groups. The case could potentially be appealed to the US Supreme Court, which could impose an even more restrictive interpretation of the EPA's role. While winning the lawsuit is not the only way to restore the EPA's authority, it is a faster and potentially more effective route. The EPA's role in regulating greenhouse gas emissions is crucial in addressing air pollution and mitigating the effects of climate change. The agency's ability to regulate emissions was previously justified by the Clean Air Act, among other factors. The lawsuit highlights the ongoing debate over the EPA's authority and its role in addressing environmental concerns. The outcome of this litigation will have significant implications for the agency's ability to regulate greenhouse gas emissions and combat climate change.