Minister of Justice Rob Nicholson announced the government's plans to appeal an Ontario court ruling that struck down key parts of federal prostitution laws. (Adrian Wyld/Canadian Press)

The federal government will appeal an Ontario court ruling that struck down key parts of Canada's prostitution laws, Justice Minister Rob Nicholson said Wednesday.

"Prostitution is a problem that harms individuals," Nicholson said in question period. "[The government] will appeal and seek a stay of that decision."

Tuesday's ruling by the Ontario Superior Court said laws against keeping a common bawdy house, communicating for the purposes of prostitution and living on the avails of the sex trade put sex workers in danger.

But NDP MP Libby Davis, a longtime advocate of sex trade workers, questioned why the government would waste money on a costly and lengthy appeal — money it could spend instead on helping affected communities.

She said the laws that were struck down don't protect society and are harmful to communities.

Earlier Wednesday, Nicholson's parliamentary secretary, Bob Dechert, told the CBC's Susan Lunn that anyone who thinks women involved in the sex trade "are not victims is very mistaken."

"There's a lot of victims in that industry and we need to protect them."

He also stressed that the ruling was the decision of one court only and should be tested in other courts.

The Superior Court judgment is subject to a 30-day stay during which the law remains in place, and the federal government can seek an extension of the stay period.

Ontario supports appeal

Nicholson had signalled Tuesday night that the Conservatives were considering an appeal, saying Ottawa would "fight to ensure that the criminal law continues to address the significant harms that flow from prostitution to both communities and the prostitutes themselves."

The government has argued that striking down the provisions of the prostitution laws without enacting something else in their place would "pose a danger to the public."

Ontario Premier Dalton McGuinty said Wednesday his government "looks forward" to supporting the Conservatives in an appeal. He said the ruling proposes some profound changes to laws that have been on the books for decades.

Click on a country's flag to read about its prostitution laws:

View The oldest profession in a larger map With files from The Canadian Press