Washington ? Taking up an age discrimination case that could make it harder for employers to accommodate older workers, Supreme Court justices expressed concern Wednesday that allowing employees in their 40s to sue for the same benefits as older workers would, as one justice said, “blow up” federal anti-age bias laws.

Several justices appeared deeply troubled by a lower court ruling that had allowed a group of employees in their 40s to seek the same accommodations from employer General Dynamics Land Systems as the company provided workers older than 50.

A Cincinnati-based federal appeals court had ruled that the workers could sue General Dynamics under the federal Age Discrimination in Employment Act, which prohibits employers from discriminating against workers over age 40. That decision produced an unusual alliance between labor organizations and pro-business groups, which contend that it would prohibit companies from ever making accommodations for older workers, because they would have to extend the same benefits to all workers over 40.

During hourlong arguments, several justices appeared sympathetic to arguments by General Dynamics lawyer Donald Verrilli, who said Congress was trying to protect older workers, or “people at the end of their working lives.”

“The problem is stereotypes — older employees don’t have the competence, productivity because they’re too old,” said Verrilli, of Chicago-based Jenner & Block.

Verrilli’s arguments clearly struck a chord with many justices. Several expressed concern that the lower court decision, if allowed to stand, would turn the anti-age bias statute on its head.

“So a piece of legislation that everyone thought was to aid older workers — especially those toward the end of their working careers — ends up harming them?” Justice Antonin Scalia asked a lawyer for the younger workers.

The statute prohibits discrimination against a worker in hiring, firing or other terms of employment “because of such individual’s age.” It covers workers who are at least 40 years old.

Mark Biggerman, arguing for the younger workers, said the federal law on the question was crystal clear. It prohibits discrimination against workers “because of their age, not because of their older age,” he said. Biggerman said the law was intended to make a person’s age a neutral factor and that special accommodations, such as flexible hours for workers over 55, would be illegal if they were not made available to all workers over 40.

But by the end of Wednesday’s argument, it was apparent the words of the statute weren’t quite so clear. Justice after justice questioned whether Congress could possibly have intended to limit an employer’s ability to help older workers.

Justice Stephen Breyer told Biggerman he feared his interpretation “will blow up this act” and produce lawsuits any time an employer “tries to be at all sympathetic.”