Washington ? The Supreme Court made it easier Thursday for police to barge into homes and seize evidence without knocking or waiting, a sign of the court’s new conservatism with Samuel Alito on board.

The court, on a 5-4 vote, said judges cannot throw out evidence collected by police who have search warrants but do not properly announce their arrival.

It was a significant rollback of earlier rulings protective of homeowners, even unsympathetic homeowners like Booker Hudson, who had a loaded gun next to him and cocaine rocks in his pocket when Detroit police entered his unlocked home in 1998 without knocking.

The court’s five-member conservative majority, anchored by new Chief Justice John Roberts and Alito, said that police blunders should not result in “a get-out-of-jail-free card” for defendants.

Dissenting justices predicted that police will now feel free to ignore previous court rulings requiring officers with search warrants to knock and announce themselves to avoid running afoul of the Constitution’s Fourth Amendment ban on unreasonable searches.

“The knock-and-announce rule is dead in the United States,” said David Moran, a Wayne State University professor who represented Hudson. “There are going to be a lot more doors knocked down. There are going to be a lot more people terrified and humiliated.”

Supporters said the ruling will help police do their jobs.

“People who are caught red-handed with evidence of guilt have one less weapon to get off,” said Kent Scheidegger, legal director of the Criminal Justice Legal Foundation.

The case provides the clearest sign yet of the court without Justice Sandra Day O’Connor.

Hudson had lost his case in a Michigan appeals court. Justices agreed to hear his appeal last June, four days before O’Connor’s surprise announcement that she was retiring.

O’Connor was still on the bench in January when his case was first argued, and she seemed ready to vote with Hudson. “Is there no policy of protecting the homeowner a little bit and the sanctity of the home from this immediate entry?” she asked.

She retired before the case was decided, and a new argument was held this spring so that Alito could participate, apparently to break a 4-4 tie.

Four justices, including Alito and Roberts, would have given prosecutors a more sweeping victory but did not have the vote of Justice Anthony M. Kennedy, a moderate conservative.