The 5-to-4 ruling allows police to use evidence from a search where they didn't first announce their presence.
Police who burst into a private building without first knocking and announcing their presence can use evidence they discover in a criminal case.
In a boost to aggressive police tactics and a setback to the privacy rights of business and home owners, the US Supreme Court has rejected the legal principle that evidence obtained in violation of the so-called knock-and-announce rule must be excluded from use at a trial.
Instead, the high court said in a 5-to-4 decision announced Thursday that such evidence can be used at trial. The social costs of excluding evidence because of a violation of the knock-and-announce rule are considerable, the high court said.
"Resort to the massive remedy of suppressing evidence of guilt is unjustified," writes Justice Antonin Scalia for the majority. He was joined by Chief Justice John Roberts, and Justices Anthony Kennedy, Clarence Thomas, and Samuel Alito.
The decision marks a rejection – in the context of knock-and-announce – of a basic safeguard in the criminal justice system established in the 1960s by the high court under then Chief Justice Earl Warren. That court adopted the approach that violations of certain procedural requirements by law enforcement officials could carry the heavy penalty of exclusion of evidence from use at a trial.
The process created an incentive for police officers to not only know the law, but to scrupulously follow it while carrying out their criminal investigations.
"The court destroys the strongest legal incentive to comply with the Constitution's knock-and-announce requirement," Justice Stephen Breyer writes in a dissent, joined by three other justices.
He says he could find no legal precedent supporting the high court's ruling in any of the Fourth Amendment privacy cases decided since 1914. "It represents a significant departure from the court's precedents," Justice Breyer writes. "And it weakens, perhaps destroys, much of the practical value of the Constitution's knock-and-announce protection."