Bite Mark Analysis: Fake Science with Real Consequences
In 1992, Levon Brooks was sentenced to life in prison for the rape and murder of a three-year-old girl. Four months after his conviction, another three-year-old girl was raped and murdered; Kennedy Brewer would be sentenced to death for this crime in 1995. Bite mark analysis played a major role in securing both of their convictions. In 2008, both men were set free and exonerated after DNA testing proved that the same man, Justin Albert Johnson, had actually killed both little girls.
Levon Brooks and Kennedy Brewer suffered years in prison for crimes they did not commit due to faulty forensic “science.” According to the Innocence Project they are not alone in their suffering, 24 people have been exonerated since 2000 after they were either convicted or arrested because of the assertions of bite mark analysts.
The scientific community has published numerous reports that have concluded that bite mark analysis is unreliable. In 2009, the National Academy of Sciences published a report, at the request of Congress, that was highly critical of a wide range of forensic specialties including bite mark analysis. The report stated that many forensic tests used to infer the source of bite marks have never been exposed to stringent scientific scrutiny. The report further stated that there is “no evidence of an existing scientific basis for identifying an individual to the exclusion of all others” when it comes to bite marks. In addition to the National Academy of Science’s report, the President’s Council of Advisors on Science and Technology, and the Texas Forensic Science Commission have all issued reports that have shown that, “no one has sufficiently proven that human bite marks are unique, or that skin is a reliable material to record them ─ or that forensic dentists can reliably identify a human bite mark in the first place.”
Despite these damning reports, as of 2018, no court has ruled against admitting bite mark analysis into evidence. One must examine how scientific evidence is admitting during litigation to understand why the courts are so hesitant to part with bite mark analysis, even after the scientific community has condemned it. The admissibility of scientific evidence is governed by Federal Rule of Evidence 702 (or the state law equivalent). The rule states that if the scientific knowledge will assist the trier of fact to understand the evidence, “a witness . . . qualified as an expert by knowledge, skill, experience, training, or education may testify [thereto] in the form of an opinion or otherwise.” In addition to 702, the Supreme Court’s ruling in Daubert v. Merrell Dow Pharmaceuticals laid out a list of factors courts should consider when determining the admissibility of scientific evidence. These factors include “whether a theory or technique . . . can be (and has been) tested;” “whether the theory or technique has been subjected to peer review and publication;” “the known or potential rate of error” of a particular scientific technique; “the existence and maintenance of standards controlling the technique’s operation;” and a scientific technique’s “degree of acceptance within [a relevant scientific] community.” The court emphasized that the analysis should be flexible and that no one factor is dispositive. 702 and Daubert gave trial judges broad discretion in admitting scientific evidence.
As a result, judges are relying on nonscientific information to determine whether scientific techniques and data should be admitted into evidence. Judges, most of whom were never trained in any scientific discipline, look to prior rulings on scientific evidence to determine whether the admit it. This has led to junk sciences like bite mark analysis to persist. For example, in 2016, a district attorney successfully argued for the admittance of bite mark evidence by saying, “this is evidence, your honor, that has been accepted for 40 or 50 years, not quite as old as I am, but 40 or 50 years, maybe longer, accepted by courts everywhere.” Because the standard has morphed into what is accepted by the legal community instead of what is being accepted by the scientific community, the ruling of a few judges who were either mislead, mistaken, or willfully ignorant of the dubious character of bite-mark analysis has allowed it to be admitted instead of condemned.
Those wrongly imprisoned are not the only victims of junk science. In the Levon Brooks and Kennedy Brewer cases, a three-year-old girl named Christine Jackson could have been saved if the investigators had not focused on Levon Brooks based on bite mark analysis. By relying on junk science, the justice system is not only letting innocent people languish in prison (or worse) but also letting guilty people go free. Additionally, by allowing dubious science to be presented as fact we are damaging both the reputation of our criminal justice system and of science in the eyes of the public.