Book Review: Failed Evidence, by David Harris

Failed Evidence: Why Law Enforcement Resists Science, by David Harris, Professor of Law at the University of Pittsburgh, concerns one of the recurrent themes of this blog—the fact that sound social science research seldom has much effect on public policy. (Check out his seven short videos dealing with main themes of the book.)

Our legal system should be undergoing a crisis of confidence as we continue to discover the number of innocent people who have been sent to jail. DNA evidence has resulted in over 300 exonerations so far, but DNA is only available in 5% of criminal cases, suggesting that we are seeing only the tip of the iceberg. Dr. Harris reviews research which casts doubt on current practices in the three areas that account for the greatest percentage of exonerations: incorrect eyewitness identifications, inaccurate forensic testing, and false confessions.

In all three areas, current practices are deeply flawed, and research suggests straightforward remedies that would greatly decrease errors. Eyewitnesses are usually shown lineups and photospreads using procedures that encourage them to pick the suspect who most closely resembles the perpetrator. The administrator knows which person is suspected and gives positive feedback if the suspect is chosen, which increases the eyewitness's certainty. Forensic tests, i.e., identification of fingerprints, firearms, hair and blood samples, etc., are inherently subjective. The reliability that is sometimes claimed for them occurs only when the second examiner is told in advance of the first one's results. False confessions occur because police question suspects for long periods of time under extreme pressure, and are permitted to lie about evidence. This produces fatigue and confusion, and some innocent suspects confess only to put an end to this painful situation. Because the idea that an innocent person might confess is counterintuitive, I've included this 10 minute video from Saul Kassin which gives further explanation of how it occurs.

Dr. Harris reviews the reasons police officers give “in their own words” for their fierce resistance to such evidence and the remedies they imply: they are too expensive, that they will allow guilty people to go free, the research is less valid than their own personal experience, etc. The most perversely amusing example of police intransigence is their inconsistent reaction to DNA evidence depending on whether it implicates or exonerates the defendant. Since their objections are easily debunked, he speculates about the real reasons for resistance.

These are divided into two categories. Cognitive reasons focus on the thought processes of the individual officer. An example is cognitive dissonance, which occurs when police are told that their past behavior may have sent innocent people to jail. This possibility is vigorously denied, and they attempt to bolster the effectiveness of current practices. Institutional reasons cite the context in which police and prosecutors work. Police officers are evaluated on the basis of the number of arrests they make and prosecurors are judged by their conviction rate. There is nothing in the system that rewards either of them for doing justice by releasing an innocent person.

Dr. Harris then lists 16 recommendations for reform, i.e., videotape all police interrogations from beginning to end, and makes some suggestions for how to make these changes happen. For example, cognitive dissonance may be minimized by focusing on the future rather than past injustices. It's at this point that Dr. Harris begins pulling his punches by compromising in advance with what he believes to be implacable resistance from the law enforcement community.

For example, the following one hour presentation by Dr. Gary Wells explains the process of relative judgment, and why we should replace simultaneous lineups, which result in identification of the suspect who most resembles the perpetrator, with sequential presentations in which the witness makes an independent judgment about each suspect. A meta-analysis of relevant studies confirms that sequential lineups greatly reduce incorrect identifications. However, they also slightly reduce correct identifications, since the simultaneous lineup results in a small percentage of “lucky guesses.” The loss of those lucky guesses is interpreted by law enforcement as letting innocent people go free, which generates resistance. Unfortunately, Dr. Harris's response to this dilemma is to suggests that this recommendation—in my judgment, the most important one of all—be optional, since it is unlikely to be accepted anyway.

By the way, here is the soon-to-be-released study Dr. Wells refers to in his lecture. The upcoming Supreme Court case he mentions did not have a satisfactory outcome.

It's clear that Dr. Harris is not optimistic about the prospects for reform. (Dr. Wells is much more optimistic.) He gives many examples in which police and prosecutors, working through their professional organizationals, have easily defeated reform attempts. The primary victims, innocent people wasting away jail, have no political clout. He ends the book with a chapter in which he presents only three cases in which meaningful reform has taken place. (The Innocence Project lists other examples.) In two of these cases, a conservative politician converted to the cause of reform and was able to use his credibility as a strong advocate of law and order to make it happen. If advocates as sympathetic to police and prosecutors as Dr. Harris are unable to bring about bottom-up change through persuasion, the best hope for social scientists may be to go over their heads, either through federal legislation or court decisions, such as the Miranda ruling, which law enforcement personnel are required to obey.