The Supreme Court reaffirmed Monday that police can enter homes in emergencies without knocking or announcing their presence.

Justices said four Brigham City, Utah, police officers were justified in going inside a home in 2000 after peering through a window and seeing a fight between a teenager and adults.

Chief Justice John Roberts, writing for the unanimous court, said that officers had a reasonable basis for going inside to stop violence, even though they could not announce their arrival over loud noise of a party.

"The role of a peace officer includes preventing violence and restoring order, not simply rendering first aid to casualties; an officer is not like a boxing (or hockey) referee, poised to stop a bout only if it becomes too one-sided," Roberts wrote.

The decision overturned a ruling by Utah's Supreme Court that said a trial judge was correct to throw out charges stemming from the police search. The trial judge ruled that police had violated the Fourth Amendment's prohibition against unreasonable searches by failing to knock before entering the house.

When the adults realized the officers were inside the house, they allegedly became abusive and were charged with disorderly conduct, intoxication and contributing to the delinquency of a minor — all misdemeanors.

In a separate opinion, Justice John Paul Stevens said that Utah courts could still find that the police entry was unreasonable under Utah's Constitution. He called it "an odd flyspeck of a case," and said he was unsure why courts had spent so much time on a matter involving minor offenses.

The Supreme Court has devoted a surprising amount of attention this year to the rights of people whose homes were searched over their objections.

In March, the court said that police cannot search a home when one resident invites them in but another tells them to go away. Last week, justices held a special re-argument to decide whether police armed with a search warrant can rush into a home without knocking and seize evidence for use at a trial.

Roberts said in Monday's ruling that officers did everything right when they arrived about 3 a.m. after getting a complaint about a loud party. They saw juveniles drinking beer in the backyard.

After seeing the scuffle through a back window, an officer opened a screen door and tried to announce the arrival of police.

"When nobody heard him, he stepped into the kitchen and announced himself again. Only then did the tumult subside," Roberts wrote. He said the officers "were free to enter; it would serve no purpose to require them to stand dumbly at the door awaiting a response while those within brawled on, oblivious to their presence."

The case is Brigham City v. Stuart, 05-502.