Admissibility of biochemical analyses results from sexual assault evidence in the United States courts.
Physiological stains in sexual assault cases have the potential to provide useful information. A comparison of genetic marker types in evidence semen stains and/or saliva stains to the corresponding genetic markers in the blood of a suspect may exclude the man as the perpetrator of the crime. If the genetic markers match, identification is inconclusive but may tend to support other circumstantial or eyewitness evidence of guilt. Potential for error is particularly high with physiological stain evidence because of its susceptibility to physical and chemical degradation. Furthermore, secretions (vaginal fluids, saliva, perspiration) from the victim are commonly mixed with the evidence specimens (semen, saliva) of the assailant. Certain genetic markers from the victim may mask those of the assailant. In many US crime laboratories there are no professional qualifications or requirements for the analysts assigned to this type of work. There is little administrative enforcement of quality control. Triers-of-fact are unaware that the data presented by the analyst are unverified and that the analyst's conclusions may be based on incorrect results.
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D001801:Blood Stains; D001826:Body Fluids / Q000032:analysis*; D005104:Expert Testimony / Q000331:legislation & jurisprudence*; D005260:Female; D005554:Forensic Medicine / Q000331:legislation & jurisprudence*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D012463:Saliva / Q000032:analysis; D012661:Semen / Q000032:analysis; D012742:Sex Offenses / Q000331:legislation & jurisprudence*; D014481:United States