An Ontario court has thrown out a drunk driving conviction against a South Asian man after finding police failed to get him an interpreter before asking him to take a breathalyzer test.

A Superior Court judge says the trial judge erred in allowing the results of the breathalyzer test to be admitted as evidence after finding that police had breached the man's right to legal counsel.

In a recently released decision, Justice David E. Harris says the trial judge was wrong to determine that the breach was mitigated because police thought they had fulfilled their duties.

Though the man spoke to a duty counsel three times, Harris says he clearly stated he did not understand and therefore police should have made efforts to rectify the issue rather than immediately making him take the test.

The decision says police had noticed the man appeared to be South Asian, had an accent and that English was not his first language, but they believed he spoke it well.

The man testified at his trial that his first language is Tamil and while he understands English, he sometimes has difficulties and has to look up words. Court heard he was not asked if he needed an interpreter.

"The law has been clear for many years that merely because the police believe they are acting within the law does not end the matter ... If this were not true, the conduct of well-meaning but blundering police officers would be given a free pass and would lie beyond the reach of Charter remedies," Harris wrote.

"The fact remains, the appellant said that he did not understand duty counsel. How could the police, hearing this statement, have an honest belief they had satisfied their obligations? The appellant's complaint remained outstanding and had not been addressed," he wrote.

"However, accepting for the purpose of argument this to be a factual finding owed deference, at the very least it was incumbent on the trial judge to delve into the reasonableness of the police belief. Instead, he accepted the honest belief of the police and looked no further."

The judge also noted that one of the arresting officers admitted that she had knowingly violated her obligations by asking the man how much he had to drink after he expressed a desire to speak to a lawyer, which Harris said "increased the seriousness" of the rights breach.

He also found that the trial judge erred in finding that the breach was lessened because police were courteous.

"The observation that the police had acted properly before they acted improperly does not significantly mitigate the seriousness of the breach," he said.