Canadian tradition holds that, in a by-election, a party leader without a seat is allowed to run unopposed by other major parties. Also, the leaders of other parties are expected not to campaign in the riding where the seatless leader is seeking election. This principle was respected by the other Quebec parties during Marois's 2007 campaign. Marois herself, however, broke with tradition when she campaigned for a PQ candidate in a by-election against Liberal party leader Robert Bourassa in 1985, as did also PQ leader René Lévesque.