Bite-mark evidence proved to be both powerful and unreliable in more than two dozen known cases of wrongful conviction. An article by Kathleen Hopkins for Gannett on this issue includes these specific difficulties relating to bite marks as evidence (Source: The Innocence Project and Dr. John Demas, a fellow of the American Academy of Forensic Sciences):
• Human skin is not a reliable medium on which to record bite marks because skin is subject to tension, distortion, swelling and elasticity.
• There have been no research studies on live humans to prove that the discipline of bite-mark analysis is scientifically reliable.
• Research on cadavers at the University of Buffalo suggests the same teeth do not make the same bite marks each time.
• Bite marks can be skewed by the movement that goes along with violent acts.
• Bite-mark analysis is subjective and prone to bias.
Read the complete article here.