Embedded Player NPR's Nina Totenberg reports on today's arguments before the Supreme Court on the constitutionality of the 1970 Clean Air Act. Opponents from industry and several state governments say Congress unconstitutionally delegated too much of its power to the executive branch. The measure requires the Environmental Protection Agency to establish air quality standards that protect the public health, based on the latest science. Defenders of the law say Congress could never agree on standards, and is justified in assigning the job to the EPA.