Canada's top court is hearing the case of two HIV-positive Canadians who did not disclose their medical condition to their sexual partners.

Lawyers for Clato Mabior are appearing before the Supreme Court of Canada Wednesday to argue that Canadian law criminalizes carriers of HIV — the virus that causes AIDS — and does not acknowledge variations in transmission levels.

Winnipeg-based Mabior was sentenced to prison in 2008 for 14 years after he was found guilty of having unprotected sex with four females and protected sex with two others, including a 12-year-old girl.

Clato Mabior, seen in a police photo, has recently completed his prison sentence and is set to be deported to Sudan in mid-February.

Mabior's convictions hinged on his failure to inform his sexual partners that he has HIV. Four of the convictions were later overturned on appeal.

None of his partners were infected with HIV as a result of their contact with him.

Transmission risk was low, lawyers argued

At the time of Mabior's appeal, court heard that medical tests showed he had a low level of infection between 2002 and 2004, the period in which the sexual encounters took place.

Mabior's lawyers argued that his risk of transmitting HIV to his partners was therefore low.

However, the Crown argued that Mabior did not ever disclose his HIV status to his sexual partners, therefore denying them the right to consent or refuse to engage in sexual activity with him.

The Supreme Court will also hear arguments from lawyers representing a Quebec woman who had unprotected sex with her former spouse without first informing him that she was HIV-positive.

'I would be very afraid for the health of Canadians, because I certainly think [requiring disclosure] would discourage testing.'—Tim McCaskell, Toronto HIV/AIDS activist

A publication ban prevents naming the woman, who is referred to in Supreme Court documents only as "D.C."

The woman was found guilty of sexual assault and aggravated assault, but that conviction was later overturned on the basis that her viral load was undetectable during the period that the charges covered.

A number of organizations will appear at the Supreme Court hearing, including the Canadian HIV/AIDS Legal Network, the British Columbia Civil Liberties Association, L'institut national de santé publique du Québec, and the Criminal Lawyers' Association of Ontario.

The court's ruling may not benefit Mabior, a Sudanese refugee, as he is set to be deported to Sudan later this month.

Deportation to Sudan

Mabior has been awaiting deportation for over a year since he completed his prison sentence. Immigration officials have been keeping him in Canada to date due to political strife in Sudan.

Tim McCaskell, a Toronto HIV/AIDS activist, warned that a decision from the Supreme Court requiring that all infected individuals disclose their condition could lead to greater risk of HIV spreading.

He reasoned that some people living with the virus may not seek diagnosis out of fear of being prosecuted in the future for knowingly carrying it.

"I would be very afraid for the health of Canadians, because I certainly think that would discourage testing," he told CBC News on Wednesday. "If people don't test, they don't get treated. If they don't get treated, the viral load increases, and then they become very infectious, and then they can't tell someone that they're positive or negative because then they don't know."

David Eby, president of the Canadian HIV/AIDS Legal Network, worries that the creation of an offence under aggravated sexual assault increases stigma against people with HIV.

The lack of clear guidelines on what constitutes significant risk is also problematic, he said, adding that the courts should consider the lowered risk of transmission when a person uses a condom or antiretroviral drugs.

"Courts have interpreted whether or not someone is wearing a condom as potentially reducing the level below significant risk, but people have also been convicted in situations where they've used a condom," Eby told CBC News from Vancouver.

He said that a law doesn't necessarily provide the public with any additional protection, and "it may in fact provide the public with a false sense of security" because people may have unprotected sex, presuming their partner must be HIV negative because a criminal offence has been created.

An estimate 75,000 people in Canada were living with HIV at the end of 2009, according to the Centre for Infectious Disease Prevention and Control.