OTTAWA - The Liberals are blasting a newly elected Conservative MP and potential Harper cabinet minister for saying the Charter of Rights and Freedoms has been a friend of criminals.

Liberal MP Justin Trudeau is criticizing Julian Fantino over comments the former Ontario Provincial Police commissioner made in his first interview since formally becoming a politician by winning a federal byelection Monday.

Fantino won southern Ontario's Vaughan riding, ending a 22-year Liberal hold on the seat. He brings tough-on-crime credentials to politics after a 40-year policing career, views he shared in a televised interview on CBC Wednesday night.

"In some cases, the Charter has been exploited and the rulings that have followed have, in fact, benefited some criminals, absolutely," Fantino said.

"The Supreme Court of Canada and other court rulings are trying to change some of the misinterpretations that have been given as to the reason, the purpose, and the mechanisms of the Charter."

The Liberals pounced quickly on Thursday, with Trudeau accusing Fantino of deliberately keeping a low profile during the byelection campaign to keep his anti-Charter views away from voters.

"Once you become a representative of the people and you are not a cop any more . . . you have to start thinking about everyone's rights and freedoms. And sometimes that means thinking about the rights of some people you don't particularly like," said Trudeau.

"That's the strength of our Charter; that's the strength of Canada as a country."

Fantino dismissed Trudeau's criticism as, "promoting the hug-a-thug philosophy." The Liberal MP had taken Fantino to task over the course of the byelection campaign for "shirking" public debate.

But Trudeau shot back, saying: "The ease with which hug-a-thug rolls off his tongue as a means of disparaging people who don't agree with him reflects poorly on him and his whole government."

Liberal MP Irwin Cotler, a human rights lawyer, said he was deeply concerned about Fantino's "erroneous beliefs" about the Charter.

In the Commons, Cotler asked Justice Minister Rob Nicholson whether he shared Fantino's "deeply flawed" views on rights. Nicholson brushed aside the question.

Fantino is drawing Liberal attention because there is widespread speculation that he will soon find himself in Harper's cabinet, as soon as January.

Harper lauded Fantino's policing career as he welcomed him to the Conservative caucus earlier this week.

"He managed to overcome two, two decades long of Liberal hold on the riding and will be an important part of our Conservative team's efforts to make sure we get these crime bills through Parliament," Harper said.

Trudeau said Fantino will have no problem fitting in with a Conservative government that has been critical of the courts and espouses a tough-on-crime agenda, predicting he will become a leading spokesman for the Tories.

"I think unfortunately his view coincides very, very much with the view the Conservative government has on the Charter, on individual rights and freedoms," said Trudeau.