The Progressive Conservatives and New Democrats ignored an appeal from Premier Dalton McGuinty not to vote for the motion, which he said could have serious ramifications for Bentley's life and career.
The contempt motion was triggered by the government's refusal to release documents on the cost of cancelling two power plants in Oakville and Mississauga.
McGuinty tried to shelve the contempt motion and send only the issue of the gas plants to committee, but the opposition parties blocked the move.
The Tories and NDP have been anxious to get the issue to committee, where they can call witnesses, including Bentley, before making a recommendation next month.
Only a vote of the full legislature could find Bentley in contempt, something that's never happened to an Ontario MPP.
McGuinty says the Conservatives "crossed a line" when they taunted Bentley, who's a lawyer, by saying a finding of contempt would kill his legal career and hurt his chances at becoming the next leader of the Liberal party.
The Tories and NDP say people are angry at the Liberals for spending hundreds of millions of dollars to cancel the two power plants just to save Liberal seats.
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