Trudeau admitted Thursday he smoked marijuana as recently as three years ago as a lawmaker, telling reporters in Quebec City he smoked marijuana at a dinner party at his Montreal home, QMI Agency reported.
"I took a puff, passed it to the next person," he said.
Trudeau said he smoked marijuana "five or six times" in his life and never used harder drugs.
His vote on the measure that ushered in mandatory minimums and increased maximum penalties for growing six or more marijuana plants brought prompted critics to call him a hypocrite.
Trudeau, son of the late Canadian Prime Minister Pierre Trudeau, admitted Thursday he'd done one thing while saying another, but said that made him "like many Canadians who take drugs without telling their employers."
His critics jumped on his admission, with Justice Minister Peter MacKay saying, "We expect better from our elected officials and rightly so."
Prime Minister Stephen Harper said Trudeau's "actions speak for themselves."
Ipso Reid pollster Darrell Bricker told Postmedia News people who are likely to vote Liberal, including urban dwellers, college-educated people and the more affluent Canadians, may consider smoking marijuana no big deal.
He said while a majority of Canadians tend to favor easing marijuana laws, Trudeau's admission could cause concern among voters he needs to build support for the Liberal Party.
"It's something that will at least get people's attention and they'll ask some questions," Bricker said. "What I'm thinking of here are immigrant voters, particularly first generation Canadians living in the [the region around the city of Toronto] and that's where the Liberals have to win."