This briefing paper is an introduction to complex scientific and social issues surrounding using scientific analysis of HIV strands in criminal prosecutions. This type of analysis is sometimes suggested as a way to support criminal convictions for HIV transmission, without reference to the scientific and public health limitations. Using plain language, the article addresses the "incorrect assumption that phylogenetic analysis can provide definitive evidence of the route, direction, and timing of HIV transmission. There are, in fact, many limitations regarding what this scientific evidence can 'prove'," and these are discussed in detail in the article.
Some examples of the limitations that should be addressed if using phylogenetic analysis in a trial are that it cannot by itself prove that transmission occurred between individuals. "Although two individuals may have HIV that appear to be very closely related, this will not necessarily be unique to the two individuals but could extend to other people who are part of the same transmission network…Consequently, it can only be used to support other evidence." Similarly, phylogenetic analysis that suggests viral relatedness does not provide any information on the direction of that transmission.
The context of the article is the criminal justice system in the United Kingdom, but the information about, and significant limitations of, phylogenetic analysis have wide ranging applicability. As described in the introduction of the article: "This short briefing paper is aimed at professionals working in the criminal justice system and HIV professionals who may be called as expert witnesses in criminal HIV transmission cases. It may also be useful for people working in HIV support organisations and HIV-positive individuals. It aims to explain how phylogenetic analysis should and should not be used in criminal trials for the reckless transmission of HIV."