World experts publish consensus statement on the science of HIV in the context of criminal law

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]

Transmission risk

The first part of the statement focuses on the factors influencing transmission risk and the risk associated with particular acts. On the basis of the best available evidence it concludes as follows:

  • Correct use of a condom prevents HIV transmission
  • Viral load that is low or “undetectable” significantly decreases or eliminates the possibility of HIV transmission
  • Pre-exposure prophylaxis (PrEP) significantly decreases the possibility of HIV acquisition
  • Post-exposure prophylaxis (PEP) significantly decreases the possibility of HIV acquisition
  • Medical male circumcision decreases the possibility of HIV transmission from women to men
  • Risk reduction practices such as withdrawal or strategic positioning decrease the possibility of HIV transmission
  • Sexually transmitted infections (STIs) can increase the possibility of HIV transmission in some circumstances

The harmfulness of HIV

The second part of the Consensus Statement recognises that "persistent misconceptions exaggerating the harms of HIV infection appear to influence application of the criminal law". This is important because, for example, if HIV infection is assumed to be a grievous (serious) bodily harm, a defendant will typically receive a more severe punishment than if it is not. The Statement emphasises the impact of effective treatment, and that in many countries people living with HIV on treatment live both well and longer. As the Statement says, "Although HIV causes an infection that requires continuous treatment with antiretroviral therapy, people living with HIV can live long, productive lives including working, studying, travelling, having relationships, having and raising children, and contributing to society". 

Proving transmission

Where HIV transmission is alleged, it is critical that there is proof beyond reasonable doubt that the defendant infected the complainant. Prosecutors will typically use medical records, sexual history, and phylogenetic analysis of HIV samples from the defendant and complainant as part of the evidence in its case. Such evidence has been misused and misunderstood in a number of cases. The Consensus Statement states that:

  • Medical records can provide contextual information but cannot establish transmission between a complainant and a defendant.
  • Phylogenetic analysis can be used as a forensic tool. The results can be compatible with, but cannot conclusively prove, the claim that a defendant has infected a complainant. Importantly, phylogenetic results can exonerate a defendant when the results are not compatible with the allegation that the defendant infected the complainant.

The Consensus Statement is a milestone in the history of HIV criminalisation, and in the campaign to ensure that people living with HIV are treated fairly in the criminal justice system. Its welcome conclusion is that "more caution be exercised when considering criminal prosecution, including careful appraisal of current scientific evidence on HIV-related risks and harms. This is instrumental to reduce stigma and discrimination and to avoid miscarriages of justice".


Barré‐Sinoussi F et al. Expert consensus statement on the science of HIV in the context of criminal law. J Int AIDS Soc, 25 July 2018,

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criminalization, criminalization of HIV transmission, criminal law, legal and policy frameworks