It's not a trick – and for would-be masked rioters, it's no treat, either.

While tens of thousands of children are putting the final touches on Halloween costumes and masks, the House of Commons has approved a bill banning people from hiding their faces during riots.

The private member's legislation, Bill C-309, is the brainchild of Alberta Conservative backbencher Blake Richards.

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Mr. Richards says it's a response to last year's Stanley Cup riots in Vancouver, when often-masked vandals rampaged through the streets after their team's Game 7 loss to the Boston Bruins.

The bill provides a penalty of up to 10 years in prison for anyone convicted of covering their face during a riot or other unlawful assembly.

The bill – which won't apply to those attending peaceful protests or demonstrations – passed by a margin of 153-126, with the government in support and the NDP and Liberals opposed.

During the Commons debate on the bill, New Democrat MP Charmaine Borg cited civil liberties concerns in opposing the measure.

"I would also like to point out that this bill takes away an individual's right to demonstrate anonymously," she said.

"An individual is not necessarily going to commit a crime just because he or she is wearing a mask at a riot. It is reasonable to think that the person just wants to remain anonymous and protect his or her identity."

Mr. Richards scorned that view.

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"Anyone who is wearing a mask or a disguise to conceal his or her face in the midst of a riot is exhibiting aggravating behaviour," he said.

He said law-abiding citizens caught up in violence will naturally tend to want to leave the area.

"It is hard to imagine that others who ignore police instructions to depart the area and who, in addition, continue to linger in the vicinity while wearing a disguise are seized by any innocent motives or good intentions in those kind of circumstances."

The bill does not apply to protests or demonstrations and contains a "lawful excuse" clause which would protect people who cover their faces for religious or cultural reasons.

Opposition Leader Tom Mulcair called the bill redundant.

"The police already have all the tools they need," he said.

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Liberal Sean Casey said the legislation is just another part of the Conservative law-and-order fixation.

"It is as if the Conservatives lie awake at night dreaming about ways to put more and more people in prison," Mr. Casey said during the debate. "It is an obsession rooted not in science or evidence, or even reason. It is irrational."