Contaminated Confessions and Other Lessons of DNA

The participants in this exchange certainly seem to have once piece of common ground: that if something does go wrong, we should try to find out what went wrong and fix it. Are we really trying, though? Who is “we”? How could we do better?

Take eyewitness evidence, ubiquitous and used in many tens of thousands of cases each year. Even in the narrow sliver of cases where post-conviction DNA testing can be done and actually is done, we know that eyewitness errors play a troubling role. There is a vast body of scientific research on how to improve identification procedures. More states and police departments have adopted best practices, and national policing organizations recommend as much and the changes are fairly simple – but progress is highly uneven. Traditional, non-blind lineups actually harm law enforcement first and foremost – because they lead to many more “filler” identifications that can “burn” an eyewitnesses credibility. Yet improving those procedures has been slow going. All this despite high profile DNA exonerations, which more than anything else involve eyewitness errors.

But since our primary topic is the death penalty, take a type of evidence more common in homicide investigations – confessions. All but two of the false confessions that I studied were contaminated – the innocent convicts were said to have confessed using details that only the true culprit could have known – we now know that could not have happened. Such was the seeming power of the confessions that quite a few were convicted despite exculpatory DNA tests; it was not until a DNA match with the true culprit occurred that they were cleared. Many hundreds of police departments now videotape entire interrogations, to ensure against contamination – but also to be able to convincingly show that they took a professional and accurate confession. Yet most do not. More states now require this simple inexpensive safeguard, but most do not. Why is that?

Finally, many thousands of cases each year – no one keeps track – are success stories where evidence like DNA clears someone early on in a police investigation. Police clear an innocent person and move on to pursue the culprit. No lessons are learned from such cases. If the eyewitness got it wrong, or the confession was false – and the error was caught – that is a great opportunity to learn from a near miss. Police convene top brass to investigate right away whenever an officer discharges a weapon. They may often conclude use of such force was appropriate – but it is seen as important to quickly find out whether something went wrong. Some prosecutors’ offices are creating conviction integrity units to do that type of work, among other things. Police could do the same. And so should public defenders. Judges are more open to claims of innocence than in the past, as well as requests for DNA testing, in part due to new statutes – but there is more they could do. It does not impugn our criminal justice system to constantly look for ways to improve it, but everyone involved needs to dedicate time and energy to asking questions when something does go wrong, or when it nearly does, but an error is avoided.

Also from This Issue

Lead Essay

  • Learning What We Can from DNA by Brandon Garrett

    Professor Brandon Garrett discusses the strengths and weaknesses of DNA as evidence. DNA offers a high degree of certainty in the cases where it is available, but in many cases, like that of Troy Davis, the DNA evidence just isn’t there. Individual exonerations are nonetheless suggestive of a wider pattern of wrongful convictions throughout the criminal justice system. It is difficult to say how large this pattern is, but DNA evidence has certainly made us aware of certain problems that existed prior to its use. Does this increase or decrease our faith in capital punishment? And where will public opinion settle? Garrett asks but does not fully answer these questions.

Response Essays

  • Rightful Convictions by Joshua Marquis

    Joshua Marquis points out that prosecutors, not defense attorneys, first demanded the introduction of DNA testing. Defense attorneys fought it—until they realized that they could sometimes use the public’s confusion about the tests to produce doubt in jurors’ minds. Still, DNA secures many more convictions than exonerations. Taken as a whole, Marquis argues that DNA evidence shows our criminal justice system to have a vanishingly low rate of wrongful convictions. He readily grants that even a tiny number of wrongful convictions is too many, and of course we should not let the guilty go free. As a result, he recommends still more extensive DNA recordkeeping and testing.

  • DNA Reminds Us That to Err Is Human by Jeffrey Kirchmeier

    Jeffrey Kirchmeier grapples with the thorny, inescapable problem of human error. He notes that DNA evidence has offered us a way to test other forms of evidence, such as eyewitness testimony and police lineups. But he moves quickly from these to still harder questions. If jurors can err on matters that admit of an objective answer, then what of the subjective questions they must also answer? The choice between capital punishment and life in prison is itself one of these subjective decisions, and it too may be flawed. Unfortunately, we have no way to test it.

  • Some Historical Notes on the Problem of Capital Punishment by George H. Smith

    George H. Smith reviews some of the key philosophical questions that have been raised about capital punishment. He discusses the views of several thinkers, including Jeremy Bentham, Nathaniel Branden, and Immanuel Kant. He also references Cesare Beccaria, who doubted the social utility of the death penalty. Even if DNA does offer certainty in the matter of guilt, Smith suggests that there may be independent and controlling reasons to reject capital punishment.

The Conversation