Washington ? Age has its benefits, the Supreme Court said Tuesday, ruling that younger workers can’t sue their employers when older colleagues get preferential treatment.

In a 6-3 decision that affects tens of millions of workers, the justices said the law that protects older employees from age discrimination doesn’t apply in reverse.

The Supreme Court ruled in a case brought by about 200 General Dynamics Corp. workers who claimed they suffered a type of reverse discrimination because they were too young to get benefits being offered to colleagues age 50 and over.

The workers, all in their 40s, sued General Dynamics when it changed its retirement benefits in 1997. Until then, longtime company employees could retire and receive full health benefits. Under the new union contract at plants in Lima, Ohio, and Scranton, Pa., only longtime workers 50 or older could receive full health benefits after retirement.

The workers claimed they were protected by the 1967 Age Discrimination in Employment Act, which forbids age discrimination of any worker 40 or older. About 70 million U.S. workers are 40 or older, roughly half the nation’s work force.

Employees who brought the case had the backing of the Bush administration, which argued that Congress meant to protect people over 40 from any type of age discrimination.

The Supreme Court, whose members’ average age is about 70, said the law “does not mean to stop an employer from favoring an older employee over a younger one.”