The fight over cars and carbon dioxide moves Tuesday from the Supreme Court to a federal courtroom in Burlington, Vt., in a case that automakers say could reshape vehicles sold on the East and West coasts.
The industry is suing to block a 2004 California regulation involving global warming. The rule would require a 30 percent cut in emissions of greenhouse gases from cars and trucks sold in Vermont and New York, which follow California's air quality rules, to be fully phased in by the 2016 model year.
In court filings, automakers have argued that regulating the emissions will increase pollution, cause more traffic deaths and lead domestic automakers to stop selling most of their passenger models in states that adopt such regulations.
The companies have disputed that global warming is a problem, even though they have acknowledged it in different forums as a serious problem. And they tried, mostly unsuccessfully, to close much of this case to the public.
"This is a huge issue to consumers, because it may well determine what vehicles are available for them to purchase," said Gloria Bergquist, a spokeswoman for the Alliance of Automobile Manufacturers, which includes General Motors, Toyota and most other large automakers. "If it's a big issue for consumers, it's a big issue to us."
Environmental groups and the offices of the attorneys general in Vermont and New York, which is a party to the case, say the automakers are overstating the complexity and hardship of such a regulation.
"It's that sky-is-falling approach, but the sky didn't fall with catalytic converters," Attorney General William H. Sorrell of Vermont said, referring to the anti-pollution technology forced on the industry in the 1970s.
Last week, in a 5-4 decision in Massachusetts v. Environmental Protection Agency, the Supreme Court ruled that the agency has the authority to regulate heat-trapping gases in automobiles. The Bush administration has long opposed that.
Instead, more than 12 states, including California, Massachusetts, New York and Vermont, have already or are in the process of moving to regulate such emissions.
California has the authority to set air-quality rules, and Northeastern states have long chosen to follow those rules instead of Washington's. The Supreme Court victory was important for the states, because the approval of the environmental agency is needed before California can regulate emissions involving global warming.
Automakers have sued to block the California regulation in federal courts in California, Rhode Island and Vermont, though only the Vermont case has gone forward. That case is scheduled to enter the trial phase Tuesday.
The battle has exposed fault lines among automakers. Two trade groups representing the major manufacturers are involved in the suit, one dominated by domestic producers and one by foreign.
They have clashed over their legal strategies, and only GM and DaimlerChrysler, two of the more outspoken companies opposing the new regulation, are directly listed as plaintiffs.