NEW YORK -- A dozen states have asked the U.S. Supreme Court to require the government to regulate vehicle emissions of carbon dioxide.
The states, along with three cities and several environmental groups, sued the EPA for failing to regulate the emissions, which scientists link to global warming.
Last August, the U.S. Court of Appeals in Washington, D.C., refused to hear the case.
The EPA said in 2003 that it could not regulate greenhouse gas emissions because Congress had not authorized it to do so under the Clean Air Act. Cars and light trucks account for 20 percent of U.S. carbon dioxide emissions.