The U.S. Supreme Court said Wednesday that federal employees who also are in the military reserve must be paid the equivalent of their civilian salaries when called to active duty during national emergencies.

The 5-4 decision could affect hundreds of thousands of people.

The justices ruled in an appeal filed by an air traffic controller who spent about five years on active duty in the Coast Guard at a pay rate lower than what he earns as a Federal Aviation Administration employee.

Congress adopted a differential pay statute in 2009, but the Justice Department argued that it only applied to people whose service had a strong connection to a national emergency. The majority disagreed, finding it applies to any reservist called up during a national emergency. — Associated Press