David Shepardson / Detroit News Washington Bureau

The auto industry lost another court battle in its bid to stop California and at least 12 other states from imposing a 30 percent reduction in vehicle tailpipe emissions by 2016.

In a 57-page opinion issued Tuesday, U.S. District Judge Anthony Ishii said California and the other states that have adopted stricter emissions rules than the federal standards can do so, throwing out a challenge by Detroit automakers.

Judge Ishii’s decision follows a trial in Vermont, which also allowed states to impose their own emissions requirements.

California is still waiting for a waiver from the Environmental Protection Agency to impose the rules beginning with the 2009 model year that starts next fall. The EPA has said it will issue its decision before the end of the year.

Under the Clean Air Act, California is the only state that can set its own vehicle pollution standards, because it started regulating air pollution before the U.S. EPA was created. Other states are free to choose either the California rules or the federal government’s.

Automakers strongly oppose the California waiver, saying it could lead to a state-by-state patchwork of regulations and prevent automakers from selling certain vehicles in certain states. They instead have endorsed a bill passed by the House last week that would increase fuel efficiency standards nationally by 40 percent to a fleetwide average of 35 miles per gallon by 2020.

The automakers contend that by 2010, California-style regulations would reduce sales by up to 10,800 vehicles. California says that by 2020 its regulation could reduce sales by 4.7 percent.

Environmentalists praised the ruling.

"This is a huge win for clean air and a cooler planet," said Vickie Patton, senior attorney with Environmental Defense. "Judge Ishii’s opinion leaves no doubt that the EPA must act now to pave the way for the innovative clean car programs."

The automakers’ trade group issued a statement saying the industry would consider its options, including an appeal of the ruling.

"We can all agree that higher fuel economy is important, but the issue here was about federal fuel economy law," the Alliance of Automobile Manufacturers said in a statement.

"Under federal law, only the federal government can set fuel economy standards for all 50 states. We need a consistent national policy for fuel economy, and this nationwide policy cannot be written by a single state or group of states — only by the federal government."

Appeal pending in Vermont

Last month, the automakers’ alliance appealed the decision that upheld Vermont’s decision to adopt California’s strict emissions standards, calling it "urgent" since new rules would go into effect next year.

Alliance president and CEO Dave McCurdy said in October that the Vermont appeal is "urgent as this legislation applies to model year 2009 vehicles, which consumers will start seeing in early 2008 — just a few months from now."

Judge William Sessions, the Vermont judge, on Sept. 12 rejected the automakers’ arguments in a case he said largely hinged on whether the regulations were too draconian for automakers to comply with.

"The court does not find convincing the claims that consumers will be deprived of their choice of vehicles, or that manufacturers will be forced to restrict or abandon their product lines," Sessions wrote in his ruling.

"The court remains unconvinced automakers cannot meet the challenge of Vermont and California’s (greenhouse gas) regulations. History suggests that the ingenuity of the industry, once put in gear, responds admirably to most technological challenges."

Automakers: Sales at stake

The auto companies said the Vermont decision would dramatically reduce sales, force them to shrink the size of vehicles and power of engines and add gasoline-hybrid engines.

In the Vermont trial, Alan Weverstad, executive director of GM’s environment and energy, testified that it could cost GM $25 billion to comply with the state’s rules, and that by 2016 the company still would be 7 mpg short of the mileage requirement.

That would force GM to stop selling in Vermont and other states that adopted the standard, which would force fuel efficiency of 43 mpg, he testified.

In turn, an expert for the state of Vermont said the regulation would add about $1,500 per vehicle. The automakers said the cost would be as much as $6,000.

The Associated Press contributed to this story.