Multi-state lawsuit challenging the federal government’s decision to delay the effective dates of final rules governing energy efficiency for six products.

Multi-state settlement of consumer-protection claims against car manufacturers that overstated their vehicles’ fuel efficiency.

Twelve states joined in defense of EPA’s new source performance standards for methane and VOC emissions from the oil and gas sector.

Settlement of consumer protection claims raised by a multi-state coalition of state attorneys general against Volkswagen for selling vehicles equipped with “defeat device” software intended to circumvent emissions standards and concealing this software from regulators and the public.

Letters and testimony providing recommendations on federal legislation amending the Toxic Substances Control Act (TSCA) to revise the process and requirements for evaluating and determining whether regulatory control of a chemical is warranted.

Group of 17 state AGs and Former Vice President Al Gore announced a coalition of states committed to taking creative steps to combat climate change, including investigations into fossil fuel companies and climate-related disclosures.

Oregon, California, and Washington joined in defense of Oregon’s Low Carbon Fuel Standard.

Oregon and Washington AGs filed multiple lawsuits against the Department of Energy (DOE) concerning the cleanup and processing of nuclear waste stored in Hanford, Washington.

Multi-state intervention to join EPA’s defense of Clean Power Plan against challenge mounted by other states and industry petitioners.

Multiple states joined as defendant-intervenors in support of EPA in lawsuit challenging New Source Performance Standards (NSPS) for carbon dioxide emissions from new and modified power plants.

Multiple sates intervened to support EPA’s defense of the Waters of the U.S. rule.

Multiple states intervened in lawsuit to defend EPA rules concerning regulation of greenhouse gas emissions from stationary and mobile sources.

Multi-state suit to compel EPA to review and revise New Source Performance Standards for wood burning devices.

Multi-state coalition reached agreement with U.S Department of Energy establishing timetable for updating federal efficiency standards for energy-intensive consumer products.

Multi-state lawsuit to force EPA to comply with Clean Air Act requirement to update and revise National Ambient Air Quality Standards (NAAQS) every five years.

Multiple states moved to intervene in litigation concerning the 2012–2016 light duty motor vehicle emissions standards.

Multi-state lawsuit challenging the adequacy of EPA’s 2006 revision to the National Ambient Air Quality Standards (NAAQS) regulating soot pollution under the Clean Air Act.

Multi-state action against EPA for failure to set NSPS standards for oil refineries.

State AGs intervened in lawsuit to defend California’s greenhouse gas emission standards for motor vehicles against challenge alleging that the standards are preempted by the Energy Policy and Conservation Act (EPCA).

Multi-state challenge to EPA denial of petition to regulate greenhouse gas emissions from motor vehicles under Clean Air Act.

Washington State intervened and multiple states submitted Amicus Briefs in lawsuit filed by Native American tribe against Canadian smelting company for polluting the Columbia River and Lake Roosevelt.