Late on August 29, U.S. Department of Justice (DOJ) representatives filed a friend of the court brief with the U.S. Supreme Court, backing an industry suit against California's South Coast Air Quality Management District (SCAQMD), reports the Associated Press.The dispute is over clean fleet rules, established in 2000 and 2001, requiring fleet operators to buy cleaner-burning alternative fuel vehicles when upgrading or expanding their fleets. The rules, which apply to buses, taxis, waste haulers and buses, have resulted in the replacement or refitting of hundreds of vehicles to use natural gas or other alternative fuels. The Western States Petroleum Association and the Engine Manufacturers Association filed suit in U.S. District Court against the SCAQMD, which prevailed in that court and in the 9th Circuit appeals court.With the Supreme Court scheduled to hear the case in December, the DOJ argued that state and local governments cannot institute their own pollution standards under the Clean Air Act. The engine manufacturers claim the rules are a de facto ban on certain engines and vehicles. SCAQMD has countered that there is no new emissions standard, the rules simply ask fleets to choose among the cleanest engines available, with a provision for exceptions when no suitable alternative is available. This is the third time the Bush Administration has weighed in on issues affecting the state's battle against the nation's worst air pollution.