<p>WASHINGTON - Lawyers for a Southern California clean air agency told the Supreme Court on Wednesday it was within its bounds when it created rules stricter than national standards to reduce the number of vehicles polluting the region's air.</p>
<p>Justices seemed skeptical of the idea that the South Coast Air Quality Management District can go beyond the federal Clean Air Act to impose tougher antismog restrictions for city buses, airport shuttles and other vehicles. An attorney for oil companies and diesel engine manufacturers argued that local pollution rules conflict with the federal Clean Air Act.</p>