Southern California air quality officials overstepped their authority when they required private trash haulers, bus lines and other companies to purchase low-pollution vehicles for their fleets, the U.S. Supreme Court ruled Wednesday.
The 8-1 decision significantly sets back a broad effort by the South Coast Air Quality Management District, the regional smog agency, to expand its reach and tackle the biggest sources of smog-forming exhaust: cars, trucks and other motor vehicles.
The federal government has primary authority over those pollution sources, and local regulators assert that federal officials are not doing enough to help clean the air in Southern California.
The ruling could also forecast trouble for other efforts by California officials to press the state's authority to push new air pollution regulations, some legal experts said.
Because Southern California has the nation's worst pollution problem, regional smog officials -- responsible for air quality in Los Angeles, Orange, Riverside and San Bernardino counties -- have long had the right to set tougher standards than the federal government for factories, power plants and other stationary sources of pollution.
But that authority does not help in handling emissions from cars, trucks and other vehicles, which account for about 70% of the region's smog.
To address that pollution, air quality regulators had argued that the federal Clean Air Act gave them the power to impose the anti-pollution requirements on fleets of vehicles. Because they were not regulating the manufacture of vehicles, just limiting the types that local fleet-owners could buy, the regulations did not overstep their power, the local regulators argued.
The Bush administration disagreed and sided with engine manufacturers and oil companies that sued the California regulators.
In the decision, eight of nine justices took the industry's side, saying Congress specifically sought to keep local officials from taking such measures when it debated the Clean Air Act.
"The manufacturer's right to sell federally approved vehicles is meaningless in the absence of a purchaser's right to buy them," Justice Antonin Scalia wrote in the court's opinion.
"If one state or political subdivision may enact such rules, then so may any other; and the end result would undo Congress' carefully calibrated regulatory scheme," he added.
Justice David H. Souter was the sole dissenter. He argued that although Congress sought to prevent local agencies from adopting regulations that resulted in a hodgepodge of engine standards around the country, AQMD officials were simply requiring fleets to choose among some current clean-engine technologies.
The Clean Air Act, he argued, does not prevent "one of the most polluted regions in the United States from requiring private fleet operators to buy clean engines that are readily available on the commercial market."
Since their adoption in 2000 and 2001, the rules have put more than 8,900 low-polluting trash trucks, transit buses, airport shuttles and passenger cars on Southern California roads, AQMD officials said.
More than 60% of the region's transit buses are running on cleaner alternative fuels, such as natural gas. By 2010, the rules were projected to erase 4,780 tons per year of polluting emissions, including 2,699 tons of carbon monoxide and 1,931 tons of nitrogen oxides, key component of smog.
The ruling comes at a time when Southern California smog fighters are losing ground in their battle to clean the air after decades of gains.
Last year, the area experienced 68 bad air days, a 28% increase from the previous year and nearly 50% more than in 2001. Last summer, air quality officials declared the first Stage 1 health alert since 1998. The public warning that the air was dangerous for everyone to breathe was one officials had thought they might never need to issue again.
The court's decision was welcomed by engine makers, who argued that the local rules prevented private companies from buying the vehicles they wanted. It was denounced by environmentalists and local air regulators, who were particularly angry that the Bush administration had entered the case on the side of industry.
California and 16 other states, along with the National League of Cities, National Assn. of Counties and National Conference of State Legislatures, had filed friend-of-the-court briefs supporting the AQMD.
"We're scrapping for every possible cost-effective pollution control strategy. Here is an example of a metropolitan area that is demonstrating leadership, and the rug is being pulled out from under them," said Bill Becker, executive director of the State and Territorial Air Pollution Program Administrators Assn. in Washington.
Regional regulators elsewhere in the country may now steer clear of innovative rules for dealing with air pollution problems in their backyards, he said.