[U.S.] Supreme Court to hear challenge to California's authority to set vehicle emissions standards

Under a provision of the Clean Air Act that was enacted in 1967, California was explicitly allowed to set its own motor vehicle emissions standards because of the unique pollution problem in the state. The problems were unique in both character and intensity because the state then, as now, had more motor vehicles than any other state in the country, and California had already enacted new air pollution standards that were actually tougher than the ones in the federal law.