Washington ? The Supreme Court restricted the free-speech rights of the nation’s 21 million public employees Tuesday, ruling that the First Amendment does not protect them from being punished for complaining to their managers about possible wrongdoing.

Although government employees have the same rights as other citizens to speak out on controversies of the day, they do not have the right to speak freely inside their offices on matters related to “their official duties,” the Supreme Court said in a 5-4 decision.

“When a citizen enters government service, the citizen by necessity must accept certain limitations on his or her freedom,” said Justice Anthony M. Kennedy, rejecting a lawsuit brought by a Los Angeles County prosecutor.

Lawyers for government whistle-blowers denounced the ruling as a major setback. They said it could threaten public health and safety. Hospital workers who know of dangers may be discouraged from revealing them, while police and public employees may be dissuaded from exposing corruption, they said.