One of the most significant events at the 22nd International AIDS Conference (AIDS 2018) was the publication of the Expert consensus statement on the science of HIV in the context of criminal law. Authored by 20 of the world’s leading scientists, and based on robust evidence, the statement counsels caution when prosecuting people for HIV transmission, exposure and non-disclosure, and encourages governments, law enforcement officers, and those working in the judicial system to note carefully advances in HIV science so as to ensure that current knowledge in this field informs the application of the law.
The statement is notable not only for its engagement with the most recent research findings, its intended global reach, and in its uncompromising recognition of the impact which the refusal to deploy, or to misuse, science can have.
Most critically, the statement is explicit that its purpose is to assist those providing expert opinion evidence in individual criminal cases, and that it is “not intended as a public health document to inform HIV prevention, treatment and care messaging or programming”. This is important. One of the errors that criminal justice and judicial authorities have made when using estimates of the transmission risk associated with particular acts is to apply population, or aggregate, risk estimates to individual people’s conduct on specific occasions. So, research using such data that indicates 80% condom effectiveness against HIV transmission during penetrative vaginal sex might be taken to suggest that on any one occasion there is a 1 in 5 chance that the receptive partner will acquire the virus. This could lead a court on an HIV exposure allegation to consider the risk to be relatively high, and so lead to a conviction.
However, as the statement explains, "if the estimated risk of HIV transmission from an HIV-positive man to a woman during a single episode of condomless vaginal sex is 0.08%, then the risk of transmission when a condom is used can be understood as at least 80% lower, or 0.016% (less than 2 in 10,000)". Further, "when other risk reduction factors are present (e.g. low viral load or withdrawal before ejaculation) the possibility of HIV transmission, even in the event of incorrect condom use, is further reduced". [References omitted]