Criticisms of the Use of Blood Pattern Analysis in the Courtroom
editBlood Pattern Analysis is one of the forensic disciplines least based upon real science. It has evolved from a collection of empirical observations that have resulted in potentially flawed inferences about the behaviour of blood outside the body. While it can be beneficial in some aspects, the use of blood pattern analysis as testimonies in the courtroom is questionable at the least. The results of simple experiments that have been done are taken by blood pattern analysis “experts” and estimated beyond what is scientifically supportable, which can then lead to a wrongful convictions. An example of where blood pattern analysis was proved wrong was the case of Warren Horinek in 1995. In this particular case, BPA was used as the sole evidence for the conviction. Both the DA and investigation officers testified for the defence, but blood spatter testimony from an independent “expert” resulted in a conviction. Despite large amounts of evidence pointing in the different direction, the BPA "expert's" opinion had a lasting impression on the jury and a potential innocent man is still in prison. In 2009, the National Academy of Sciences released findings of large study conducted in forensic science, stating that the “uncertainties associated with bloodstain pattern analysis are enormous,” and concluding that the opinions of blood pattern experts are “more subjective than scientific.” Thus, the use of them for testimonies in the courtroom should be taken with caution.[1] In other studies it has been found that contextual information can influence the interpretation of blood patterns. Analysts can be exposed to information such as police investigators’ theories, witness statements, type of injuries sustained by the victim, or the type of weapon used. The contribution of this can result in the analyst's examination of the blood pattern to be influenced by the contextual information [2] [3] It should also be noted that only two of the professional organizations for blood pattern “experts” have any requirements for membership, and only one of them has an educational requirement.