We’ve previously discussed some of the myths surrounding forensic science, particularly the idea that it is a foolproof way to solve crimes, but it’s worth noting that one of the most widely recognized forensic specialties, blood splatter analysis is also one of the most questionable. Here’s why criminal attorneys think the technique isn’t as reliable as most people believe.
The Birth of Blood Splatter Analysis
ProPubica recently wrote an article detailing the birth and spread of the questionable technique. Essentially, the field was created in the basement of a chemist named Herbert MacDonell fascinated with what blood could reveal about a crime scene. He soon began experimenting with splatters and eventually wrote books on the subject, representing himself as an expert on the science without ever having his laboratory or findings certified or peer-reviewed. Because of his scientific background and the way he presented himself, judges accepted his findings and few appellate courts overturned cases based on his testimony -despite having practically no proof outside of his word that the results were accurate. As courts accepted blood splatter analysis as a legitimate science, it set a legal precedent making it harder and harder for defense lawyers and other attorneys to reject such claims.
MacDonell also started teaching courses in this new field, certifying police officers as experts after only a 40 hour course. While MacDonell advertised his scientific credentials as an expert witness, his blood splatter students didn’t need to have any minimum educational background in order to be certified. After teaching classes for 38 years, only 5 students failed to pass.
Questioning the Science
While blood splatter is backed by the courts due to legal precedent, a 2009 report by the National Academy of Sciences (NAS) found that expert’s opinions were generally “more subjective than scientific.” The report also determined that a capable analyst should have an understanding of applied mathematics, significant figures, the physics of fluid transfer and the pathology of wounds -things that aren’t covered during a 40 hour workshop to become a certified blood splatter analyst and few people taking the courses already have. In fact, MacDonell testified against the findings of many of his own students, proving both how subjective the findings can be as well as the fact that a scientific background should be mandatory for someone hoping to understand such intricate details as where blood lands and drips after a homicide.
The findings attracted the attention of the Department of Justice(DOJ), which commissioned its own study on the accuracy of the field. The DOJ determined that the hypothesis that serve as the foundation for blood splatter analysis are still largely untested and subject to assumption and errors of the analyst. Analysts almost never properly account for gravity and also make assumptions about how speed influences blood splatter while this has never been proven.
Despite these findings, courts continue to allow splatter experts to testify and jurors are inclined to believe the testimony of “experts” after seeing shows like CSI, Law & Order and Dexter discuss how useful blood splatter can be in solving a crime. Even if a blood splatter analyst is permitted to testify against you though, a top attorney can either discredit the witness by showing the findings of the NAS and DOJ, or by introducing a blood splatter expert that disagrees with the findings of the analyst presented by the prosecution.
Improving Blood Splatter Analysis
With the damning findings of the NAS and DOJ, more is being done to reduce the inaccuracies of blood splatter analysis. More study is being performed on fluid dynamics to provide a further scientific background to the field.
Some locales are also creating mandatory educational requirements for analysts as well. In Texas, for example, anyone testifying about blood splatter analysis in court will need to have a four year degree in natural or forensic science as of May of 2019.
It’s important to remember that just because a field of science seems legitimate on TV shows doesn’t mean it holds up in the real world. If you have been accused of a crime and believe blood splatter evidence could be used against you, do not speak to police without a criminal lawyer present. You can schedule a free initial consultation with Peter M. Liss by calling (760) 643-4050 or (858) 486-3024.
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