British AIDS advocates are speaking out against the United Kingdom’s first hepatitis B transmission conviction, reports. This case—the first prosecution against another sexually transmitted disease other than HIV—involved a 29-year-old man who was found guilty of grievous bodily harm for infecting his female partner. He was sentenced to serve two years in prison.

Organizations that oppose the court’s ruling are raising questions about the case. Advocates believe that the defendant was tricked into a confession after he was told that scientific tests claimed that his strain of hepatitis B matched hers. Yet, it has been shown that phylogenetic analysis—tests that compare DNA and protein sequences—cannot successfully determine transmission between two different people.

“We have serious concerns as to whether the new prosecution guidelines were properly followed in this case,” said Yusef Azad of the National AIDS Trust. “We note as in the first HIV cases that it is a migrant who is targeted; we challenge the severity of the two year prison sentence for hepatitis B, which in adults is…treatable.”