California won a major victory in its campaign to regulate greenhouse gases at the US Supreme Court in Washington on Monday but the battle is not over, according to a leading state newspaper.

The Los Angeles Times (LAT) said the state [which pioneered vehicle emissions laws in the US] still faces challenges on two fronts – at the US Environmental Protection Agency (EPA) and in a lawsuit by automakers – before it can implement its landmark law slashing greenhouse gas emissions from car exhaust.

Even if California prevails, the congress could end up passing weaker national legislation that would supersede the state’s, the paper noted on Tuesday.

“I think it’s a very tough call right now,” Harvard University environmental law professor Jody Freeman said when asked by the LAT whether the state’s mandate to have cleaner cars on the road by 2009 would be met. “I don’t think the chances are great, because I think there’s reason to believe Congress will act before EPA.” Freeman filed a brief supporting greenhouse gas regulation in the case decided on Monday by the Supreme Court, the LAT said.

According to the paper, others, however said the defeat suffered by the motor industry and President Bush’s administration at the hands of the high court should greatly improve the chances of California, and several other states that seek to follow its lead, in curtailing gases that contribute to global warming.

At a San Francisco news conference, state attorney general Jerry Brown was reported to have called the ruling a “resounding affirmation of California’s actions to address global warming.” Brown’s office is defending the state’s statute against the automakers’ lawsuit, the Los Angeles Times said.

The newspaper said the automakers argue in several pending cases that state regulation of greenhouse gases is illegal because it amounts to regulating the fuel efficiency of cars and only federal transportation officials can do that.

The Supreme Court ruled on Monday that greenhouse gases can be regulated as air pollutants. For the EPA to regulate, it must first determine that science shows global warming is harmful to human health and welfare, the report said.

But Freemand told the Los Angeles Times that, even if the EPA decides greenhouse gases should be regulated to protect public health, the agency could still deny California’s long-delayed request to implement its own law by saying that the problem is global and not unique to the state.

California currently has more stringent standards for vehicle exhaust emissions than the federal law, and several other eastern seaboard states have followed its lead.

The Los Angeles Times said that, because of California’s extreme air pollution and existing laws, it was granted the right under the Clean Air Act to pass its own air pollution rules, provided the federal government signs off with a waiver. Other states can then follow California’s lead, and 10 have passed such laws and are waiting for the waiver.

To get a waiver, California must show compelling and extraordinary conditions, Freeman told the newspaper.

“California is special. It’s the only state in the country that can set tailpipe standards separate from federal standards,” she told the LAT. “Everything depends on that waiver.”

The report said state governor Arnold Schwarzenegger, who broke with [Republican] President Bush by endorsing California’s Democratic majority-sponsored emissions law, wrote to the president and the EPA a year ago asking them to grant the state’s request to implement its own law.

According to the LAT, the governor noted that California’s emissions standards would begin with 2009 vehicles and cut global warming emissions nearly 30% by model year 2016.

An EPA spokeswoman, Jennifer Wood, on Monday told the newspaper that the agency had been reviewing the complex issues in the waiver request and would soon solicit public comments and hold hearings.

Schwarzenegger reportedly issued a statement Monday saying he was “encouraged” by the court decision.

“We expect the US EPA to move quickly now in granting our request for a waiver, which will allow California and … other states that have adopted our standards to set tougher vehicle emissions levels,” the Los Angeles Times cited the statement as saying.

But some experts have said that, because global warming is not just a California problem, its argument for special status might not work this time, the paper added.

Environmental lawyers and legislators on Monday told the LAT that certain states, however, do have a special problem with global warming, particularly California.

David Bookbinder of the Sierra Club, one of the lead attorneys on the Supreme Court case, and former assemblywoman Fran Pavley, author of California’s tailpipe legislation, told the Los Angeles Times that, because the Sierra Nevada snowpack, which provides crucial drinking water to Californians, is thinning and because warmer summer temperatures could increase the state’s still-high smog [air pollution] levels, California’s plight is unique.