The 5-to-4 decision left uncertain the value of the "knock-and-announce" rule, which dates to 13th-century England as protection against illegal entry by the police into private homes.
Justice Antonin Scalia, in the majority opinion, said that people subject to an improper police entry remained free to go to court and bring a civil rights suit against the police.
But Justice Stephen G. Breyer, writing for the dissenters, said the ruling "weakens, perhaps destroys, much of the practical value of the Constitution's knock-and-announce protection." He said the majority's reasoning boiled down to: "The requirement is fine, indeed, a serious matter, just don't enforce it."
The decision followed a reargument less than a month ago, with the newest justice, Samuel A. Alito Jr., evidently casting the decisive vote. Justice Breyer's dissenting opinion was clearly drafted to speak for a majority that was lost when Justice Sandra Day O'Connor left the court shortly after the first argument in January.
The justices' lineup in this case, which upheld a Detroit man's conviction for drug possession, may become a familiar one as the court proceeds through its criminal-law docket. In addition to Justice Alito, those who joined the majority opinion by Justice Scalia were Chief Justice John G. Roberts Jr. and Justices Clarence Thomas and Anthony M. Kennedy. Justice Breyer's dissenting opinion was joined by Justices John Paul Stevens, David H. Souter and Ruth Bader Ginsburg.
The decision answered a question that the court had left open in 1995, when it held in a unanimous opinion by Justice Thomas that the traditional expectation that the police should knock and announce their presence was part of what made a search "reasonable" within the meaning of the Fourth Amendment. The amendment bars unreasonable searches.
In that case, Wilson v. Arkansas, the court declined to say what the remedy should be for a violation of the knock-and-announce rule. Ordinarily, evidence that is seized illegally — in the absence of a warrant, for example — may not be used at trial, under what is known as the exclusionary rule.
By a strong majority, most state and federal courts that have considered the issue have applied the exclusionary rule to violations of the knock-and-announce requirement. In its decision on Thursday in Hudson v. Michigan, No. 04-1360, the Supreme Court upheld a ruling by the Michigan Court of Appeals, one of the few courts to have rejected the exclusionary rule in this context.
In the case, the Detroit police had a warrant to search for drugs in the home of Booker T. Hudson Jr. At his unlocked door, they announced their presence, but did not knock and waited only three to five seconds before entering, not the 15 to 20 seconds suggested by the Supreme Court's precedents.
Had the police observed a longer wait, they would have executed the search warrant and found the evidence anyway, Justice Scalia said. That made the connection between the improper entry and the discovery of the evidence "too attenuated" to justify the "massive remedy of suppressing evidence of guilt."
Justice Scalia said the knock-and-announce rule was designed to protect life, property and dignity by giving the homeowner time to respond to the knock and eliminating the need for the police to break down the door. But he said the rule has never protected "one's interest in preventing the government from seeing or taking evidence described in a warrant."
Throughout his opinion, Justice Scalia made clear his view that the right at issue was a minimal, even trivial, one — "the right not to be intruded upon in one's nightclothes," he said at one point — that could not hold its own when balanced against the "grave adverse consequences that exclusion of relevant incriminating evidence always entails."
The majority opinion was sufficiently dismissive of the exclusionary rule as to serve as an invitation to bring a direct challenge to the rule in a future case.
Justice Scalia surveyed changes in the legal landscape since 1961, when the court in the landmark case Mapp v. Ohio made the exclusionary rule binding on the states. Noting that the purpose of the exclusionary rule was to deter constitutional violations by making them costly for the prosecution, Justice Scalia said there was less need for deterrence today, when the police are better trained and when the ability to bring civil rights suits against the government has greatly expanded. Under current federal law, he noted, successful civil rights plaintiffs are reimbursed for their attorney fees.
The conditions that made deterrence necessary "in different contexts and long ago" no longer exist, Justice Scalia said, adding that a strict application of the exclusionary rule as envisioned by the court in 1961 "would be forcing the public today to pay for the sins and inadequacies of a legal regime that existed almost half a century ago."
It is rare to find Justice Scalia, a self-described "originalist," incorporating evolving conditions into his constitutional analysis. Almost always, when the court in a constitutional case takes account of changing conditions, the result is an expansion of constitutional rights, rather than, as Justice Scalia advocated in this case, a contraction.
One puzzling aspect of the decision was a concurring opinion by Justice Kennedy, who said that he wished to underscore the point that "the continued operation of the exclusionary rule, as settled and defined by our precedents, is not in doubt." Nonetheless, he signed the part of Justice Scalia's opinion that suggested that the exclusionary rule rested on an increasingly weak foundation.
Justice Breyer argued that "the court destroys the strongest legal incentive to comply with the Constitution's knock-and-announce requirement. And the court does so without significant support in precedent."
He called the majority's argument "an argument against the Fourth Amendment's exclusionary principle itself," adding, "And it is an argument that this court until now has consistently rejected."