Clean Air Act
The Attorney General has long played a leading role in ensuring that the U.S. Environmental Protection Agency (EPA) carries out its duties under the federal Clean Air Act.
In 2004, EPA took the position that it had no power under the federal Clean Air Act to regulate greenhouse gas (GHG) pollution, forcing Massachusetts, California and other states to file suit. In April 2007, the U.S. Supreme Court ruled that greenhouse gases are "air pollutants" under the Clean Air Act. Read the Supreme Court's decision, pdf. As a result of California’s victory in Massachusetts v. EPA, EPA began regulating GHG pollution.
California has supported EPA's actions to regulate greenhouse gas emissions against industry challenge. For example, certain industry groups sued EPA over its 2009 determination that greenhouse gas pollution threatens the public health and welfare of current and future generations. This "endangerment determination" is a prerequisite to any Clean Air Act regulation of greenhouse gas emissions from vehicles. California intervened with 17 other states to defend EPA. In addition, California supported EPA in its efforts to "tailor" the requirements of the Clean Air Act so that they better apply to GHG emissions from stationary (non-vehicle) and industrial sources. On June 26, 2012, the D.C. Circuit Court of Appeals called the endangerment determination "unambiguously correct"and upheld the agency’s regulatory actions. Read the decision, pdf. On October 15 2013, on industry’s petition, the Supreme Court granted review on only one issue: Whether EPA permissibly determined that its regulation of GHG emissions from new motor vehicles triggered GHG permitting requirements under the Clean Air Act for stationary sources (such as factories and power plants).
The Attorney General has encouraged EPA to regulate not only greenhouse emissions from motor vehicles (see “Clean Cars”), but also from other types of vehicles (vessels, aircraft, and non-road vehicles) and power plants.