California policymakers and environmentalists view recent Supreme Court actions as a small victory for clean air, but worry about future legal challenges.

The Supreme Court declined Monday to take up an appeal from conservative states challenging California’s ability to establish strict vehicle emission rules that effectively set the standard for the rest of the nation.

Supreme Court dismisses a red-state constitutional claim that targeted California's power to fight air pollution.

The Supreme Court on Monday declined to take up a business-backed appeal that could make it easier to challenge California’s vehicle emissions standards.

Critics of the state's power to set stricter air pollution standards than the federal government say they hope the justices will address the issue in the

The Supreme Court says it will take up a business-backed appeal that could make it easier to challenge federal regulations, acting in a dispute related to California’s nation-leading standards for veh

The U.S. Supreme Court agreed on Friday to hear a bid by fuel producers to challenge California's standards for vehicle emissions and electric cars under a federal air pollution law in a major case testing the Democratic-governed state's power to fight greenhouse gases.