Forensic Hair Evidence in Criminal Trials: Admissibility, Reliability and the Risk of Wrongful Convictions

Abstract

Hair forensic evidence has helped criminal investigation and law enforcement agencies over the years to identify suspects or victims and in certain cases, to exonerate suspects, but the use of such evidence in court has led to many wrongful convictions. This is particularly evident in cases using microscopic hair comparison data because the probative value attached to such forensic evidence had been inflated by the hair experts or the chemist themselves to the extent that it dilutes any probability of unreliability that could exist in relation to such evidence. The court had relied entirely on such forensic evidence as the truth without venturing into its reliability. This is because the laws in some countries, such as Malaysia, allows the court to make a presumption that such evidence is credible if the hair analysis is done by the government appointed forensic official. Therefore, it is essential that the admissibility and the probative value of such hair evidence are scrutinised by the court in each and every case, particularly the way in which these forensic experts carry out forensic tests, as the technology and technique with regard to such analysis are evolving.