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.

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 states intervened in lawsuit to defend EPA standards regulating mercury and other air pollutants from the power sector.

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

Multiple states intervened in lawsuit to support EPA rule on cross-state air pollution against state and industry challenge.

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 request for EPA to issue methane standards under the Clean Air Act.

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 challenge to EPA decision to remove fossil fuel-fired power plants from list of sources regulated under CAA section 112 (hazardous air pollutants) and to establish new performance standards for mercury emissions from these plants under CAA section 111.

Multi-state litigation under Clean Air Act alleging violations of New Source Review permitting process to reduce sulfur dioxide emissions in coal-fired power plants.

Multi-state challenge to 2002 EPA rule amending and expanding the routine maintenance, repair and replacement exceptions to the New Source Review program.

Multi-state challenge to 2002 EPA rule amending the New Source Review (NSR) program and narrowing the definition of “modification” to exclude certain sources from NSR requirements.