By ADAM LIPTAK

Bradley Harrison was driving from Vancouver to Toronto in 2004 with 35 kilograms of cocaine in the trunk when a police officer pulled him over, found the drugs and arrested him.
A year and a half later, an Ontario trial judge ruled that the officer’s conduct was a “brazen and flagrant violation of Mr. Harrison’s rights. The officer’s explanation for stopping and searching Mr. Harrison - confusion about a license plate - was contrived , the judge said, and the search “was certainly not reasonable.
In the United States, that would have been good news for Mr. Harrison. Under the American legal system’s exclusionary rule, the evidence would have been suppressed as the result of an unlawful search.
But both the Canadian trial judge and an appeals court refused to exclude the evidence. Mr. Harrison was sentenced to five years in prison.
“Without minimizing the seriousness of the police officer’s conduct or in any way condoning it, the Court of Appeal for Ontario ruled in Mr. Harrison’s case in February, “the exclusion of 77 pounds of cocaine, with a street value of several millions of dollars and the potential to cause serious grief and misery to many, would bring the administration of justice into greater disrepute than would its admission.
The case is now before the Canadian Supreme Court. The United States is the only country to take the position that some police misconduct must automatically result in the suppression of physical evidence. The rule applies without regard to the gravity of the crime or the power of the evidence.
“Foreign countries have flatly rejected our approach, said Craig M. Bradley, an expert in comparative criminal law at Indiana University. “In every other country, it’s up to the trial judge to decide whether police misconduct has risen to the level of requiring the exclusion of evidence.
But there are signs that some justices on the United States Supreme Court may be ready to reconsider the American version of the exclusionary rule. Writing for the majority two years ago, Justice Antonin Scalia said that at least some unconstitutional conduct ought not require “resort to the massive remedy of suppressing evidence of guilt.
The court will soon have an opportunity to clarify matters. The justices will hear arguments on October 7 about whether methamphetamines and a gun belonging to Bennie Dean Herring, of Brundidge, Alabama, should be suppressed because the officers who conducted the search mistakenly believed he was subject to an outstanding arrest warrant as a result of careless record-keeping by another police department.
Elsewhere in the world, courts have rejected the automatic exclusion of improperly gathered evidence.
The European Court of Human Rights, a notably liberal institution, refused in 2000 to require the suppression of illegally obtained evidence. Some specialists in comparative criminal law say that the decentralized nature of American law enforcement requires a more rigorous and consistent approach to deterring misconduct. The law enforcement systems in Canada and England, by contrast, are notably less fragmented and may be subject to more stringent professional discipline.
But not always. The officer who pulled over Mr. Harrison’s car in Ontario thought the car should have had a front license plate, even though the car was from Alberta, which does not require one. Supporters of the American practice say that only strict application of the exclusionary rule can effectively address violations of the Fourth Amendment, which bans unreasonable searches and seizures.
“The exclusionary rule deters police misconduct in a straightforward and effective way,’’ said a supporting brief filed by the National Association of Criminal Defense Lawyers in the case the Supreme Court will hear in October.
Several justices have questioned whether the rule still makes sense in light of what they called the increased professionalism of the police and the availability of alternative ways to punish misconduct, including internal discipline .
Opponents of the rule say it is indirect, incomplete and in a way perverse. Even if it deters unlawful searches, exclusion of evidence, for instance, offers no remedy to innocent people whose rights were violated by unlawful searches.
More important, as Justice Robert H. Jackson wrote in 1954, the exclusionary rule “deprives society of its remedy against one lawbreaker because he has been pursued by another.
But most specialists continue to support the rule, said Orin S. Kerr, a law professor at George Washington University in Washington. “The U.S. experience is a consequence of history, Professor Kerr said. “It’s a response to the police not following the law in the absence of this remedy.