The U.S. Supreme Court on Thursday preserved a California law banning the sale of pork in America's most-populous state from pigs kept in tightly confined spaces, rejecting an industry challenge claiming that the voter-backed animal welfare measure impermissibly regulates out-of-state farmers.

The justices upheld a lower court's decision to dismiss a lawsuit by the National Pork Producers Council and the American Farm Bureau Federation seeking to invalidate the law. The industry had argued that the measure violated a U.S. Constitution provision called the Commerce Clause that courts have interpreted as empowering the federal government - not states - to regulate interstate commerce.

(Reporting by Nate Raymond in Boston; Editing by Will Dunham)