BROSSARD, Que. -- Justin Trudeau won't say if Bill C-51 -- the controversial anti-terror bill introduced by the Conservatives -- is constitutional, even though the Liberals backed it in Parliament.

At a morning campaign event Thursday, he said his party will always defend the Charter of Rights, enacted when his father was prime minister in 1982.

But the Liberal leader would not clearly weigh in on the constitutionality of the anti-terror legislation, which has been questioned by some legal experts and the New Democrats who refused to support the bill.

"That's a debate that's ongoing, but the fact is the Charter of Rights and Freedoms is there to ensure that our rights are not violated, that we are protected," Trudeau told reporters.

"The Liberal party will always defend the Charter of Rights and Freedoms at the same time as we defend Canadians' security ... we don't have to make a choice between one or the other."

Bill C-51 has created political ripples in Quebec, where Trudeau has spent most of the week campaigning.

In March, the Quebec government indicated it had serious concerns with the Conservative bill and criticized the federal government for failing to consult the provinces before drafting the legislation.

To that end, three Quebec ministers sent a sharply worded letter to federal ministers which was also tabled in the national assembly.

It said the Quebec government had "many concerns" with C-51.

"It is worrisome that the bill gives CSIS such vast powers, including the possibility to take certain actions that violate the Canadian Charter of Rights and Freedoms and Canadian law," the letter stated.

The NDP, which dominated the political landscape in Quebec in the last federal election, has promised to repeal the legislation if it forms the government after Oct. 19.

Trudeau is to meet Montreal Mayor Denis Coderre on Thursday before moving on to Toronto.

This morning, he announced a Liberal government would ditch the proposed toll system for the Champlain Bridge.