MONTREAL - Canada's highest court is set to hear arguments over whether it's a crime for people with HIV to keep their condition from their sexual partners if the risk of transmission is low.

Supreme Court justices are to hear two cases Wednesday, both appeals from Manitoba and Quebec, which hinge on the obligations of those with the virus that causes AIDS.

Protestors set up in front of Montreal's Quebec Superior Court on Tuesday, arguing that a life-time jail sentence for aggravated assault isn't helpful for someone with AIDS.

Jordan Arsenault sported a red net on his face Tuesday to bring attention to his objection to the harsh charges on those who transmit the virus.

"This is to represent the anonymity and stigma that affects HIV positive people due to the criminalization of non-disclosure," said Jordan Arsenault.

The argument is that the virus is no longer necessarily a killer as one of his co-demonstrators explained.

"Science has changed and right now controlled medication will lessen the amount of virus in someone's virus and prevent the virus from being spread," said Michael Foster of AIDS Community Care Montreal.

At the Supreme Court, prosecutors argue that people carrying HIV must always inform their partners regardless of the risks of transmission. That way partners can decide if they want to run the risk of contracting the virus.

Advocates supporting people with HIV argue that such thinking criminalizes carriers of the virus and doesn't acknowledge the science that can determine the likelihood of transmission.

All are looking to the Supreme Court to clarify the law and update a high court ruling from 1998 which has been interpreted differently by judges across the country ever since.

"There is a high level of uncertainty among people living with HIV regarding when they are required under the criminal law to disclose their HIV-positive status," said Cecile Kazatchkine, policy analyst with the Canadian HIV/AIDS Legal Network.

"The uncertainty in the law is creating great fear in the community. People need to know what could put them at risk of prosecutions."

One of the cases involves Clato Mabior, a Winnipeg immigrant who was originally convicted of six counts of aggravated sexual assault and sentenced to 14 years in prison for failing to disclose his illness to numerous partners. Four of those convictions were overturned by the Manitoba Court of Appeal, which found not everyone who had sex with Mabior was exposed to "significant risk."

Mabior was undergoing anti-retroviral therapy and used condoms in a few of his encounters. None of his partners tested positive for HIV, the court noted.

In the Quebec case, a woman carrying HIV met her partner in 2000 and did not disclose her illness the first time they had sex. After she told him, the two stayed together for four years and separated when she accused him of domestic violence. He then went to police and accused her of failing to disclose her illness.

She was found guilty of aggravated assault and sexual assault, but the convictions were overturned by Quebec's Court of Appeal. The court found the odds of transmission at the time were low. Crown prosecutors appealed to the Supreme Court.

"There is no real consent if the sexual partner is not informed of the HIV-positive status of the other," they say in their submission. "Having HIV is a sad diagnosis which brings constraints to the person who has it. The infected person must confront this illness with courage. It is utopian to think the infected person can have a sex life similar to that of someone who is not infected."

The Crown compared it to a parent's decision to vaccinate a child.

"The choice belongs to the person who assumes the risk."

But lawyers for Mabior and the Quebec woman, who cannot be named, both argue such a sweeping responsibility for disclosure unfairly strips those carrying HIV of their right to privacy. This could have a chilling effect which could "discourage people from being tested and treated for HIV and further endanger both themselves and the public," Mabior's lawyers argue in their submission.

Condom users or those who have a low enough viral load to make transmitting the disease unlikely should not be punished, they argue. Criminalizing everyone who has sex without disclosing their HIV would "open the floodgates" to ridiculous prosecutions.

"It will serve only to turn law abiding citizens into criminals regardless of their efforts to protect their partners by complying with public health advice on HIV prevention. Such a result would shock the community and serve only to further stigmatize the virus and anyone living with it."

Defence lawyers for the Quebec woman echo those arguments. They say Canada lags far behind other countries when it comes to HIV infections. The law is crying out for modernization and clarification of what constitutes "significant risk," they say.

"We submit that only the actual intentional transmission of the virus should be criminalized, as in most of the Commonwealth countries."

With files from The Canadian Press.