State AG Database – Defense of Federal Standards

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The following is a list of actions taken by state attorneys general to defend federal environmental standards against challenges aimed at eliminating or rolling back those standards, organized by topic:

Air Pollution

Michigan v. EPA, 135 S.Ct. 2699 (2015): Multiple states intervened in lawsuit to defend EPA standards regulating mercury and other air pollutants from the power sector.

EPA v. EME Homer City Generation, 134 S.Ct. 1584 (2014): Multiple states intervened in lawsuit to support EPA rule on cross-state air pollution against state and industry challenge.

Climate Change Mitigation

North Dakota v. United States Environmental Protection Agency (D.C. Cir. 2015): Multiple states filed amicus brief in support of EPA in litigation challenging New Source Performance Standards (NSPS) regulating carbon dioxide emission from new and modified power plants

West Virginia v. EPA (D.C. Cir. Oct 23, 2015): Intervention to join EPA’s defense of Clean Power Plan against challenge mounted by other states and industry petitioners.

Utility Air Regulatory Group v. EPA (2014): Multiple states intervened in lawsuit to defend EPA rules concerning regulation of greenhouse gas emissions from stationary and mobile sources.


American Public Gas Assoc. v. Department of Energy, 2014 WL 316551 (C.A.D.C., April 24, 2014): Multi-state intervention in support of Energy Department proposed rule setting efficiency standards for residential gas furnaces.