A v The Queen

The appeal concerned a conviction and sentence for sexual offences. The central issue revolved around the admissibility and direction to the jury concerning evidence of *trichomonas vaginalis* found in both the complainant and the appellant. The Court of Appeal of the Northern Territory was tasked with determining whether the trial judge's directions regarding this evidence were adequate and whether any failure to properly direct the jury constituted a miscarriage of justice.

The legal issues before the court were whether the evidence of *trichomonas vaginalis* had sufficient probative value to be considered by the jury, and if so, whether the jury was adequately directed on how to use that evidence. Specifically, the court had to consider if the evidence established that the appellant had the infection at the times of the alleged sexual intercourse, or if it merely showed a recent infection with no clear link to the alleged offences. The court also had to assess the potential for this evidence to unfairly prejudice the appellant, particularly given the limited corroborating evidence for the complainant's account.

The court reasoned that while the complainant and the appellant both tested positive for *trichomonas vaginalis*, the evidence did not establish that the appellant had the infection at the time of the alleged sexual intercourse. Scientific evidence indicated that the infection in males is typically short-lived and that the appellant's urethral swab was taken at least eight months after the last alleged sexual contact. The court found that the evidence of the infection had little probative value in proving the alleged offences and was highly prejudicial. Consequently, the trial judge's failure to direct the jury to disregard this evidence, or at least to carefully consider its limited relevance, resulted in a miscarriage of justice.

The appeal was allowed, the convictions were quashed, and a retrial was ordered.