Forensics is the application of principles from other disciplines, usually sciences, to the law. In addition to the analysis of blood, urine, fingerprints, body decomposition, blood splatter, and the presence of drugs and drug metabolites, forensics have been applied to linguistics (determining who composed a document based on the language used), psychology (someone’s mental state as either the perpetrator or the victim of a crime), engineering (whether a structure was sound), and many other subdivisions of science.
Two things to understand about forensics in the criminal courtroom: 1) juries love the seeming certainty of “science,” and 2) it’s often completely bogus.
Forensics makes for great television: in “true crime” shows such as “Forensic Files,” “CSI: Crime Scene Investigations,” “Cold Case Files,” and even the classic “Quincy, M.E.” science provides simple, definitive answer to what had seemed complicated and messy.
In real life, the application of science in the courtroom is compromised by the presence of . . . lawyers. Well, not the presence of lawyers, per se, but the fact that the science is filtered through lawyers (some of whom are judges, but judges are lawyers). Before science is allowed into the courtroom, it has to be vetted by lawyers for whether it conforms to the rules of evidence and other indicia of what is considered reliable in a court of law. The people making these determinations are trained in law, not science. As a result, bad science is admitted into courtrooms.
In 2016, the President’s Council of Advisors on Science and Technology (staffed by professors of various scientific disciplines from the most prestigious universities, as well as private institutions such as Kaiser Permanente School of Medicine and United Technologies Corporation) released a damning report on forensic sciences in the courtroom. It found that bite mark analysis, hair comparisons, latent fingerprints, firearms and spent ammunition (a/k/a ballistics), toolmarks, shoeprints, tire tracks, and handwriting comparisons lacked any scientific foundation or verifiability (“foundational reliability” in science-speak). In other words, testimony that a hair fiber matches someone’s hair or that bite marks came from a particular set of teeth (the suspect’s) are opinions unsupported by scientific rigor or verifiability.
Yet, these opinions are often offered with near certainty that the “science” behind them does not support. That is why, in 2015, the FBI admitted that “nearly every examiner in an elite FBI forensic unit gave flawed testimony in almost all trials in which they offered evidence against criminal defendants over more than a two-decade period before 2000.” Generally, this flawed testimony was testimony that pattern matches (what they look for when comparing tire tracks, fabric fibers, finger prints, ballistics, and other disciplines in which two items are compared) were “nearly perfect” or “certain” or otherwise without doubt a match when the science is nowhere near that conclusive.
And that’s not even delving into malfeasance: biased or incompetent scientists in crime labs in North Carolina, Texas, Massachusetts, New Jersey, and others have been fired or even arrested due to falsifying scientific testimony or taking shortcuts. Remember, these government scientists are paid by and work for the government (as in State v. Defendant): their job is to help get convictions. As a defense attorney, I have to hire outside, independent labs and experts because the government scientists will not testify for the defense.
Closer to home, in 2012, Minnesota stopped using a DWI breath testing machine (the Intoxilyzer 5000 EN) because the manufacturer would not disclose the computer code it used to calculate breath alcohol (so they would testify in court that the machine produced a certain measurement but they would not say how the machine got that measurement). That machine had used infrared technology to calculate the amount of alcohol in a breath sample. Infrared technology detects how much stuff that fits the molecular signature of ethyl alcohol (the intoxicating chemical in drinks) interferes with the beam of infrared light before it reaches the other end of the machine where it is collected and measured. However, other substances with a similar size can also interfere with the beam, and those substances are also counted as alcohol in infrared testing devices.
The Minnesota crime lab (the Bureau of Criminal Apprehension or BCA) then replaced that machine with one that uses two testing methods (infrared and fuel cell). The purpose of the second technology (fuel cell) was (to quote from the BCA’s own website) to “prevent interfering chemicals from adding to the alcohol result” (that is, overstating the alcohol content of the breath) which was an acknowledged error with infrared-only technology. They admit that infrared overstates how much alcohol is on a driver’s breath (“add[s] to the alcohol result”). Unfortunately, the fuel cell proved to be unreliable so the BCA turned off the fuel cell in every single breath testing machine in the State of Minnesota. So we are left with a test that by BCA’s own admission sometimes “add[s] to the alcohol result,” that is, it reports a higher breath alcohol content than is accurate. Roughly thirty-five thousand Minnesotans are charged with DWI, most based on the results of that machine, every year.
Fortunately, science sometimes produces results that lead to justice. DNA – although only relevant in a small number of cases – is reliable when performed correctly and interpreted right. So far, the Innocence Project has helped exonerate 362 innocent people, many of whom were convicted using the unreliable sciences. Unfortunately, judges are the gatekeepers of what gets into the courtroom as evidence, and Minnesota judges still allow junk science debunked by the President’s Council of Advisors on Science and Technology, the National Research Council, the FBI, itself, and numerous books as evidence in criminal cases.
Do you have questions about how science is used in the courtroom? Want to talk about science in your DWI? Give me a call.