OTTAWA - The Supreme Court of Canada has dismissed a series of complaints against a lawyer who was found to have breached the rules of civil courtroom behaviour during his aggressive but successful defence of a man charged in the billion-dollar Bre-X mining fiasco.

In a split decision, the justices sided with Joe Groia, a prominent Toronto-based securities lawyer.

The Law Society of Upper Canada found Groia breached civility rules and at one point suspended him for two months and ordered him to pay $247,000 in costs -- later reduced to a one-month suspension and $200,000.

The Supreme Court says the law society's finding of professional misconduct was unreasonable because Groia's actions were based on a sincerely held -- but erroneous -- legal belief.

The court ruled 6-3 in Groia's favour, although one judge in the majority had differing reasons.

The case involved a 10-year fight, pitted Groia against the society that regulates lawyers in Ontario, ate up millions in legal fees and was the subject of a split finding by the province's top court, which agreed his courtroom conduct was out of line.