It's ''even money" whether the government's new prostitution bill, if passed in its present form, will pass constitutional muster in any future Supreme Court challenge, according to Carissima Mathen, a law professor at the University of Ottawa.

Mathen said in a phone interview she thinks the government has "upped the ante" by criminalizing the buying of prostitution, although she also cautioned she thinks the balance is tilted towards decriminalization.

Most of Canada's previous prostitution law was struck down by the Supreme Court in December.

Although the act of prostitution was legal under the old law, the top court ruled, in a unanimous decision, laws surrounding the activity of prostitution were putting prostitutes in danger, contrary to their rights of security guaranteed by the Constitution.

The court threw out the laws against operating a bawdy house, communicating in a public place for the purposes of prostitution and living on the avails of prostitution. It noted these laws, some which dated back to British law from the 1600s, were meant to prevent a public nuisance.

"Parliament has the power to regulate against nuisances, but not at the cost of the health, safety and lives of prostitutes," the court said.

"That does not mean that Parliament is precluded from imposing limits on where and how prostitution may be conducted," it concluded, giving the government a year to come up with a new law.

New bill makes buying sex illegal

The government's response was introduced last week in the form of Bill C-36, which if passed, would create the protection of communities and exploited persons act. The proposed act would make the buying of sex illegal, as well as the advertising of it, although a prostitute is not prohibited from personally advertising sexual services.

Janine Benedet, a law professor at the University of British Columbia, thinks the prohibition against buying sex from prostitutes may hold up constitutionally.

"It's a blanket prohibition on purchasing sexual services in any location. So the old laws were very much about where you were. There's none of this, 'Well, it's OK if you do it to these women in these places.' It's 'No, the act of buying women in prostitution needs to stop.'"

Benedet, who represented the Women's Coalition for the Abolition of Prostitution at the Supreme Court hearing that resulted in the old laws being abolished, said the government has stated its goal is to drive down the demand for prostitution by criminalizing the clients.

"It's never happened before," she said in a phone interview from Vancouver. "We've never had a statement of objective [in a bill about prostitution].

"There are interesting discussions to be had about how reducing the demand for prostitution reduces the demand for sex trafficking," she said.

Ban on prostitution if minors nearby

But Benedet has a problem with another part of the new bill that makes it a crime to communicate or solicit for prostitution in any place where someone under 18 may reasonably be expected to be present.

"That's potentially a very broad prohibition," she said. "And in the name of protecting the community fabric or the interests of children, you cannot be in an awful lot of places. It's hard to imagine what's left except industrial or on the docks sorts of areas."

Benedet pointed out the government states in its preamble to its bill that it is concerned about the "exploitation" and "risks of violence" prostitutes face. "It makes no sense to criminalize them for being in specific locations, for being exploited on a residential street as opposed to an industrial area," she said.

Mathen thinks the Supreme Court expressed the most concern about the vulnerability of street prostitutes, and may not look kindly on the new bill's purpose of shielding people who happen to be nearby and are under 18 if sex workers are forced out of public places into risky locations.

Mathen thinks the prohibition against advertising for sexual services may violate the right to freedom of expression.

But, the government has "changed the discussion," she says, by being willing to say "we think the behaviour itself is wrongful and we're willing to first of all tackle the johns."

She added, "The court is not likely to say [the government] is just acting in bad faith."

Mathen said a court challenge, starting in a lower court after a criminal charge is laid, could take three or four years, unless someone launches a test case first.

Of the three sex workers who challenged the old law in a test, two had never been charged and had left the business although they stated they might return to it.

This time, Benedet says she hopes the inevitable challenges to Bill C-36 come in the form of men being charged. "So at least they're not invisible like they were in the last round," she said.

The government is planning to take its prostitution bill to second reading on Wednesday. There may also be some rare summer sessions of the House of Commons justice committee to aid in meeting the government's goal to have the bill passed in the fall.