OTTAWA - The need to acquire crucial evidence is no excuse for police misconduct that tramples Charter rights, says Canada's top court.

The Supreme Court of Canada on Friday threw out a drug conviction linked to a cocaine seizure worth up to $4 million because the police search "flagrantly" breached the suspect's Charter protections.

The high court ruled 6-1 to acquit Bradley Harrison of all charges.

It was one of four judgments handed down Friday that clarify legal limits for judges and police when it comes to evidence obtained through detention or searches that cross the Charter line.

The rulings underscore that any breach of rights must be carefully balanced against the value of the evidence and the facts of each case.

In the Harrison case, the high court overruled both the trial judge and the majority of the Ontario Court of Appeal in stressing that a provincial police officer went too far.

"While an officer's 'hunch' is a valuable investigative tool -- indeed, here it proved to be highly accurate -- it is no substitute for proper Charter standards when interfering with a suspect's liberty," wrote Chief Justice Beverley McLachlin for the court.

The judgments come at a time when the Harper government is in the midst of a law-and-order crackdown, especially for drug crimes. Vancouver in particular has suffered a recent spate of gang shootings linked to the marijuana and narcotics trade.

"It is true that the public interest in having the case adjudicated on its merits favours the admission of the evidence, particularly in light of its reliability," McLachlin acknowledged.

"On the other hand, the impact on the accused's rights, while not egregious, was significant. Bulking even larger, however, was the police misconduct involved in obtaining the evidence. This was far from a technical or trivial breach."

Rather, it involved "brazen and flagrant" disregard of Harrison's rights against arbitrary detention and unreasonable search and seizure, she said, quoting the trial judge.

Nonetheless, both the trial judge and the majority of the Ontario Court of Appeal swept aside those violations. Both deemed that the value of the evidence mitigated those tactics -- a rationalization that critics likened to knee-capping the Charter.

On Oct. 24, 2004, the Ontario Provincial Police officer stopped the Dodge Durango near Kirkland Lake, Ont., that Harrison and a friend had rented two days earlier at the Vancouver Airport. The constable had noticed the vehicle was missing a front licence plate.

He quickly realized, however, that the Durango was registered in Alberta and didn't require a front plate.

That's where the matter should have ended, wrote McLachlin. Instead, the officer told court that since he already had his lights flashing, the "integrity" of the police required he pull the vehicle over.

Harrison said he couldn't find his driver's licence. A computer search revealed that it was suspended. The officer arrested Harrison on that basis, but then said he searched the vehicle in hopes of finding the lost licence -- even though it was by now irrelevant.

Two cardboard boxes in the back of the SUV contained 35 kilograms of cocaine with a street value of up to $4 million.

Harrison was originally sentenced to five years in prison.

Dissenting Justice Marie Deschamps would have upheld his conviction.

"This is a case in which excluding the evidence will have a negative effect on the confidence of an objective person, fully informed of all the circumstances, in the administration of justice."

In one of Friday's companion rulings, the high court ruled 7-0 to uphold convictions against Donnohue Grant, saying his rights were justifiably violated when police stopped him on a Toronto sidewalk for no particular reason.

The young black man, then 18, was stopped on foot by police patrolling a high-crime neighbourhood at lunchtime on Nov. 17, 2003. One of the plain-clothes officers later told court that he thought Grant looked fidgety and had stared at them.

On that suspicion alone, one of the officers blocked Grant's path and asked for his name and address while two others stood behind him. Grant was told to keep his hands in front of him and was asked if he had anything with him that he shouldn't.

Grant eventually said he had a small bag of pot and a loaded revolver, and was arrested. He was later charged with five gun offences and sentenced to a year in jail.

The high court ruled that Grant -- being young, inexperienced and faced with three policemen -- was improperly "detained" in the sense that, while he was not physically under arrest at first, he likely felt he had no choice but to speak to the officers.

"Psychological detention is established either where the individual has a legal obligation to comply with the restrictive request or demand, or a reasonable person would conclude by reason of the state (police) conduct that he or she had no choice but to comply."

That said, the police breach in this case was not "egregious," the court ruled, in allowing the evidence against Grant.

The judgment sets out a new test to help police and judges determine what constitutes police detention and the admissibility of evidence seized as a result.