Supreme Court of Canada rules that condoms alone do not prevent a 'realistic possibility' of HIV transmission

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The Supreme Court of Canada stated on Friday that individuals who know they are HIV positive are liable to criminal prosecution for aggravated sexual assault if they do not disclose this fact prior to sex that may risk a "realistic possibility of transmission of HIV".

The unanimous decision rejected the Government's argument that there should be a blanket law requiring people with HIV to disclose regardless of the risk, stating that the duty for an HIV-positive individual to disclose can be exempted, but only when a condom is used and the individual also has a low viral load.

The court also reaffirmed the 1998 Supreme Court ruling (R v Cuerrier), which established that a person who knows they are living with HIV has a duty to disclose their HIV-positive status before engaging in conduct that poses a 'significant risk' of HIV transmission.



In HIV, refers to the act of telling another person that you have HIV. Many people find this term stigmatising as it suggests information which is normally kept secret. The terms ‘telling’ or ‘sharing’ are more neutral.


A healthcare professional’s recommendation that a person sees another medical specialist or service.


In HIV, usually refers to legal jurisdictions which prosecute people living with HIV who have – or are believed to have – put others at risk of acquiring HIV (exposure to HIV). Other jurisdictions criminalise people who do not disclose their HIV status to sexual partners as well as actual cases of HIV transmission. 

oral sex

Kissing, licking or sucking another person's genitals, i.e. fellatio, cunnilingus, a blow job, giving head.


A patient’s agreement to take a test or a treatment. In medical ethics, an adult who has mental capacity always has the right to refuse. 

Non-disclosure (regardless of whether this is active deceit or simply no verbal discussion of HIV risk) will continue to be treated as fraud that invalidates consent to sex. If it can also be shown that the sexual partner would not have consented had they known the accused was HIV positive, this is considered aggravated sexual assault, which carries a maximum sentence of life imprisonment and registration as a sex offender.

'Significant risk' versus 'realistic possibility'

Chief Justice Beverley McLachlin, writing the decision for the court, appreciated that the 1998 Cuerrier decision was not explicit enough regarding what constitutes a 'significant risk' of HIV transmission and acknowledged that this has led to inconsistent and overly broad interpretations by Canada's police and lower courts.

Although the 1998 decision had suggested that the "careful use of a condom" may lower the risk so that it is no longer 'significant', this was not binding. In recent years, courts have convicted HIV-positive individuals for having sex with a condom and/or oral sex alone while others have been acquitted for unprotected anal sex

The two cases under review by the Supreme Court – R v Mabior and R v DC  – had previously been subject to rulings at the Courts of Appeal of Manitoba and Quebec, respectively, which found there was no duty to disclose when a condom was used or when the individual with HIV had an undetectable viral load at the time of the alleged exposure.

A 2011 study, not cited the by the court, found that the lack of clarity over the duty to disclosewas resulting in "anxiety [and] confusion" for people living with HIV and led to "contradictory HIV counselling advice" by healthcare workers.

In setting the new precedent, the court stated that "condom use is not fail-safe" and referred to a 2002 Cochrane systematic review of condom effectiveness in reducing heterosexual HIV transmission which concluded that consistent use of condoms results in 80% reduction in HIV incidence.

Despite also noting the results of the HPTN 052 study, the court referred to expert witness testimony from the original 2008 trial, which stated that relying on a low or undetectable viral load that results from antiretroviral therapy was not "a safe-sex strategy".

"However, on the evidence before us, the ultimate percentage risk of transmission resulting from the combined effect of condom use and low viral load is clearly extremely low – so low that the risk is reduced to a speculative possibility rather than a realistic possibility," wrote Chief Justice Beverley McLachlin for the court.

The court did not set an actual level for an acceptably low viral load, but offered a description, based on the evidence of the Mabior case. "When a patient undergoes antiretroviral treatment, the viral load shrinks rapidly to less than 1,500 copies per millilitre (low viral load), and can even be brought down to less than 50 copies per millilitre (undetectable viral load) over a longer period of time. This appears to be scientifically accepted at this point, on the evidence in this case."

Nevertheless, the court left open the possibility of adapting to future changes in scientific knowledge about HIV-related risks and the long-term effects of living with HIV, which it noted was "indisputably serious and life-endangering. Although it can be controlled by medication, HIV remains an incurable chronic infection that, if untreated, can result in death."

More prosecutions likely

The court also addressed – and firmly rejected – public health arguments against overly broad criminalisation of HIV non-disclosure and potential or perceived HIV exposure. "The only 'evidence' was studies presented by interveners suggesting that criminalization 'probably' acts as a deterrent to HIV testing," wrote Chief Justice McLachlin. "The conclusions in these studies are tentative and the studies were not placed in evidence and not tested by cross-examination. They fail to provide an adequate basis to justify judicial reversal of the accepted place of the criminal law in this domain."

Legal scholar, Isabel Grant, whose recent article exploring the issues faced by the Supreme Court was extensively referred to in the R v Mabior decision told Postmedia news that she expected to see more criminal cases under the new interpretation of the law. "They pretty much went as far as they could have gone in the direction of criminalization,” she noted.

A coalition of HIV and human rights organisations led by the Canadian HIV/AIDS Legal Network, which acted as interveners in the two cases, issued a statement saying it was "shocked and dismayed" at the ruling, calling the decision "a major step backwards for public health and human rights".

They noted that the court's standard of a 'realistic possibility', was "an illusory limit to the criminal law [that] blatantly ignores solid science and opens the door to convictions for non-disclosure even where the risk of transmission is negligible, approaching zero".

In making the rulings, the court upheld an appeal court decision to acquit 'D.C.', a Montreal woman accused of not disclosing her HIV status to her former partner, based on the fact that she had an undetectable viral load and used a condom, but reinstated three convictions against former Winnipeg resident, Clato Mabior, who was deported to South Sudan in February.