Learning What We Can from DNA

DNA has forever altered the death penalty debate—but how and why? Two death penalty cases illustrate what DNA tests have done to affect some death penalty cases, but not others. In this essay, I compare the DNA exoneration of Kirk Bloodsworth with the case of Troy Davis, who was not exonerated by DNA or anything else. Very few death penalty cases—and homicides generally—have testable DNA evidence, but a small number of cases that do have resulted in exonerations, raising larger questions that have had a broad impact on the public and policymakers. This has produced legislative efforts to make the death penalty more accurate, fascinating debates among judges and policymakers, and changes in public attitudes. DNA and accuracy can cut both ways for those who want to abolish the death penalty and also for those who want to defend the institution.

Kirk Bloodsworth was the first person exonerated from death row based on post-conviction DNA testing. What is an exoneration? The word exoneration refers to an official decision to reverse a conviction based on new evidence of innocence. Kirk Bloodsworth was sentenced to death for a Maryland rape and murder of a nine-year old girl in 1984. How was he convicted? Five eyewitnesses placed him near the crime scene, and the prosecution put on testimony by a forensic analyst claiming to modestly link a shoe print to Bloodsworth. His conviction was reversed on appeal, where the Maryland Court of Appeals found that the prosecutors had concealed evidence.[1]

At his second trial he was not sentenced to death, but to life in prison. This time, the conviction stuck. Indeed, the Maryland Court of Appeals upheld the trial court’s refusal to allow an expert to testify about the dangers of eyewitness misidentifications. The trial judge excluded this testimony on the grounds that such evidence would be unnecessary and would “confuse or mislead” the jury.[2] We now know, of course, that the jurors were in fact gravely misled when they believed the eyewitnesses in that case. Yet that decision is still the law in Maryland.

I will return to the state of the death penalty in Maryland. We know far more now about the fragility and malleability of eyewitness memory. As in Bloodsworth’s case, it is a red flag if eyewitnesses are initially uncertain but become more certain at trial. Social scientists have powerfully shown just how malleable and fragile eyewitness memory is. Few police departments had written procedures on how to properly conduct lineups in the 1980s, and few were aware of how powerfully police can affect and even alter the memory of an eyewitness, just based on how they conduct an identification procedure. For example, at least one of the eyewitnesses recalled being told to pick out the person he had seen, not that the suspect might or might not be present in the set of photos. In addition, each had only had a brief look at the man they saw near the crime scene.

In 1993, Bloodsworth was released based on DNA tests by Dr. Edward Blake. The finding was then confirmed by the FBI and he was pardoned. At the time of Bloodsworth’s trial, no testing was done on semen stains on the victim’s underwear. While prosecutors had said none were found, Dr. Blake later reported that the stains had been circled yet apparently never tested by the FBI.[3] It also took some time for those DNA results to be run in the DNA databank. Years later when this was done, they matched another man in the databank, who was charged and pleaded guilty to the murder in 2004. Bloodsworth had been imprisoned at the same time as that man and had even delivered the actual killer books from the prison library. That man was a known serial rapist, who lived near where the victim lived, had committed sexual assaults in the area, and had just been released from jail before the murder. Perhaps if properly done, the forensics would have excluded Bloodsworth at the time of trial, and perhaps police would have turned to other leads and caught the culprit—or perhaps not.

Another more recent death penalty case also involved multiple eyewitnesses: the case of Troy Davis. His case was a far more typical murder, a shooting of an off-duty police officer intervening in a fight at a Burger King parking lot, where there was no physical evidence to do DNA testing on. There were no forensics, except some ballistics on bullets at the scene. Instead, as a federal court found, the case “center[ed] on eyewitness testimony.”[4] However, after trial, seven of the nine witnesses at trial recanted and new witnesses implicated another man. The original eyewitness identifications were themselves troubling, just as in the Bloodsworth case, and suggestive procedures were used. Immediately after the murder, police had made a five photo array with Davis’ picture in it. Yet they waited several days to show it to the eyewitnesses. In the meantime, wanted posters with that same photo were plastered all around the neighborhood and ran widely in the media. Witnesses saw those photos and later described pressure to identify Davis.

Three key eyewitnesses, before they were asked to look at the lineup or photo array, were brought back to the crime scene for a staged reenactment. The police tried to get the eyewitnesses to agree one who was standing where. They placed one man, who Davis’ lawyers maintained was the real perpetrator of the murder, to play the role of an innocent bystander in this reenactment. Perhaps as a result, their initially inconsistent stories started to merge. Later they were shown photo arrays, which were not conducted properly in a double-blind fashion; many departments still have not improved their eyewitness identification procedures. Some of these eyewitnesses recalled at trial being uncertain about whether the shooter was Troy Davis, or even being unable to identify him initially; after all, they were under stress, perhaps focusing on a weapon, in the dark, and their initial descriptions were erratic. But at trial they were sure.[5]

However, there was no physical evidence to test in Troy Davis’ case. Although the Supreme Court, in a rare move, granted a habeas petition filed directly with the Court and asked a district judge to look into the new evidence of innocence, courts ultimately did not believe the eyewitness recantations had enough weight to justify relief, and the Georgia Board of Pardons denied clemency (interestingly, after deciding it did not have time during its hearing to hear from a leading expert on eyewitness memory). Troy Davis was executed in September 2011, despite national and international attention to the case. We will never know for sure, of course, if he was innocent.

We do know a substantial amount about the unreliability of eyewitness identification evidence, particularly where police use suggestive procedures.

I read the trials from the cases of the first 250 people exonerated by DNA testing when writing my book Convicting the Innocent.[6] Like Kirk Bloodsworth, more than three-fourths of those people had eyewitnesses in their cases. Still more troubling, 36 percent had multiple eyewitnesses who got it wrong, some as many as three or four of five. Nearly all had eyewitnesses who were positive at trial that the defendant was the person they had seen commit the crime. Yet 57 percent had not been certain when they first identified the defendant; they became certain by the time of trial. And suggestive procedures were used in 78 percent of the trials that I studied, although none had re-enactments staged with multiple eyewitnesses like in Davis’ case. Far more subtle and unintentional police procedures can cause eyewitnesses to identity an innocent man.

Revelations of innocent persons on death row have permanently altered the death penalty debate. Regardless of whether one believes that the death penalty is justified in some circumstances, the knowledge that innocent people have been sentenced to death can shake one’s confidence that the death penalty can be soundly imposed. A few DNA exonerations have involved crimes that carried the death penalty. Seventeen of the exonerees were sentenced to death, and several came within days of execution. Often it was sheer fortuity that at the eleventh hour, crime scene evidence was discovered that could be DNA tested. As we have seen, the vast majority of capital cases do not involve biological evidence that can be DNA tested. The exonerees’ cases suggest others on death row might also be innocent, but again, we will never know how many. Capital convictions are notoriously reversal prone. Many of the DNA exonerees who had been sentenced had their convictions reversed even before they were exonerated, and endured two or even three trials before they were ultimately freed by DNA tests.

Six of the seventeen death penalty exonerations involved jailhouse informants. Seven involved false confessions, three of which were confessions by mentally disabled persons. Eleven were cases in which the post-conviction DNA testing not only exonerated the defendant but identified the actual perpetrator. One of the most haunting features of these exonerations is that so many were discovered by chance. Most convicts who seek post-conviction DNA testing cannot get it. Some lingered in prison for years waiting to get DNA tests or even after they obtained the DNA results.

The few but powerful examples of DNA exonerees who faced execution despite flawed evidence in their cases have influenced judges and policymakers. Let’s start with judges. Perhaps most prominent case, Baze v. Rees, saw U.S. Supreme Court Justice Stevens announce his opposition to the death penalty, citing evidence from DNA exonerations. He wrote:

[G]iven the real risk of error in this class of cases, the irrevocable nature of the consequences is of decisive importance to me. Whether or not any innocent defendants have actually been executed, abundant evidence accumulated in recent years has resulted in the exoneration of an unacceptable number of defendants found guilty of capital offenses.[7]

Similarly, federal district judge Jed Rakoff struck down the federal death penalty, arguing: “We now know, in a way almost unthinkable even a decade ago, that our system of criminal justice, for all its protections, is sufficiently fallible that innocent people are convicted of capital crimes with some frequency.” His ruling was later reversed by the Second Circuit Court of Appeals.[8]

Other hardened judges remain untroubled by DNA exonerations, inside or outside the death penalty context. For example, Justice Scalia has suggested (quoting Oregon district attorney Joshua Marquis), focusing on exonerations and the death penalty, that known wrongful convictions are an inconsequential percentage, an error rate of “.027 percent—or, to put it another way, a success rate of 99.973 percent,” if one divides exonerations by the fifteen million felony convictions during the same time period.[9]

Should we really be so reassured by Justice Scalia’s lopsided choice of numerator and denominator? Unfortunately, the argument raises even more cause for concern. I wholeheartedly agree that we should broaden the frame and look at error in cases beyond death penalty cases and beyond known wrongful convictions. However, not only are those millions of cases not a relevant comparison group, but we have never examined those millions of felony convictions.

Most murder cases do not have biological evidence linked to the perpetrator, and most police in the 1980s did not routinely save evidence after a conviction. The DNA “truth-machine” is only useful in a tiny sliver of criminal cases, and these are mostly not death penalty cases. Instead, these tend to be rather unusually serious cases, chiefly from the 1980s before DNA testing was common, that involved a sexual assault and a stranger-perpetrator, and a long enough prison sentence that the convict was still challenging the case by the 1990s when the technology fundamentally changed.

Moreover, we know that some innocent people never try to get DNA testing. Some may become discouraged; it often takes many years to get the DNA test, and some prosecutors continue to oppose relief even in relatively straightforward cases where the DNA is clearly linked to the culprit. It some cases, including many involving a confession, it takes a DNA “hit” on the actual culprit to finally bring judges and prosecutors around. Obviously there is luck involved in the actual culprit committing another crime and getting a profile entered in the DNA databanks.

Death penalty cases can involve a range of error, moreover, that do not involve innocence in the narrow sense of “Is this the person that did it?” Only some murders are eligible for the death penalty, and the sentencing question places jurors in the position of deciding whether this murder was serious enough to deserve the ultimate punishment. A convicted murderer may not be innocent of murder, but may be “innocent” of the death penalty, if this murderer did not clearly deserve to be singled out for the death penalty for a variety of reasons. The Court has confronted many cases, for example, where the defense lawyers failed to tell the jury about the defendant’s severe and abusive upbringing that might explain the vicious behavior. And that said, many noncapital cases may involve serious “innocence of sentence” claims that do not receive the same attention, but that may deserve it.

Death penalty cases may be more likely to produce exonerations simply because death row prisoners tend to have lawyers; most prisoners have no lawyer during habeas proceedings, much less investigators who can try to uncover new evidence of innocence. Innocence projects can help, but they are selective and have very long waiting lists. We may simply know more about death penalty exonerations because of the legal and judicial attention they receive. Focusing just on known death penalty DNA exonerations in the subset of death penalty cases where there was a rape and where DNA testing could potentially be conducted raises wider concerns, as Michael Risinger has developed.[10] Focusing on the larger set of death penalty exonerations also suggests an intolerable exoneration rate, as Sam Gross and Barbara O’Brien have developed.[11]

Looking beyond death penalty cases, DNA testing suggests more about the criminal cases where a DNA test can more commonly be useful, chiefly rape cases. A federal inquiry conducted in the mid-1990s, when police first began to send their samples for DNA testing, found that 25% of “primary suspects” were cleared by DNA before any trial. We have just learned that a recent retesting effort in Virginia has uncovered 76 cases of convicted felons excluded by DNA. According to Urban Institute researchers, these include 37 who are likely innocent—out of just 219 cases in which they obtained a DNA result one way or the other.[12] These people had never even asked for DNA testing, but they may be innocent. I hope there is not is anything approaching a 17% wrongful conviction rate in Virginia or anywhere else—but such disturbing numbers suggest the need for a serious government response. There has been none so far.

Reacting in part to these exonerations, however, states in numbers not seen in decades have adopted reforms and even moratoria on the death penalty. This began in Illinois, with then governor George Ryan announcing a moratorium and, on his last day in office, commuting the sentences of all prisoners on the Illinois death row. The Illinois Commission on Capital Punishment, the first innocence-related commission in the United States, issued a report with detailed recommendations for reform, some of which were adopted. Others attempted to create a “bullet-proof” and more accurate death penalty. The presence of highly probative scientific evidence, such as DNA, can also reinvigorate support for the death penalty. After all, in some cases, as Justice Scalia has noted, it can provide a “scientific means of establishing guilt” and a “highly effective way to avoid conviction of the innocent.”[13]

A 2009 Maryland law followed that approach, narrowing the death penalty and limiting its imposition to cases with certain types of forensic or video evidence, including voluntary videotaped interrogations.[14] The hope was to limit death sentences to cases with more reliable evidence. However, the statute is highly ambiguous; not all “biological evidence” is reliable like DNA tests can be, and what if the video evidence does not shed much light on guilt either? The Massachusetts Governor’s Council on Capital Punishment recommended a series of detailed reforms that would, if the death penalty were reinstated, limit it to cases where there was greater confidence in the accuracy of the verdict. The proposal failed and the death penalty was not reinstated. In contrast are states like Florida, Texas, and Virginia. These all carry out the death penalty and have large death rows; despite high-profile death-row DNA exonerations, no such reforms have been adopted there.

The public has apparently been increasingly concerned. The more recent national and international attention to the Troy Davis case provides one example. Polls also suggest that exonerations may explain lagging public support for the death penalty. Moreover, fewer death sentences continue to be sought and imposed (additionally, violent crime continues to fall). The cost of death penalty trials may play an increased role in public perceptions. However, DNA exonerations may not. There will be fewer and fewer DNA exonerations, since most occur in old cases, while DNA testing is now routine during criminal investigations. Will the impact of exonerations fade over time?

Neither death penalty states nor non–death penalty states have taken much in the way of action to prevent types of errors that can cause wrongful convictions. More police departments and states do record interrogations and have adopted best practices for eyewitness lineups. A few have also improved quality control and standards for forensics. Those reforms are inexpensive and they strongly benefit law enforcement; they help to identify the guilty as well as clear the innocent. Much more remains to be done. In death penalty and in non-death penalty cases, we can do better to get it right.

[1] Bloodsworth v. State, 512 A.2d 1056 (Md. 1986).

[2] Bloodsworth v. State, 543 A.2d 382 (Md. App. 1988).

[3] Stephanie Hanes, ’84 Investigation Quick to Overlook the Culprit, Baltimore Sun, May 22, 2004.

[4] In re Davis, NO. CV409-130, 2010 WL 3385081 *1 (S.D.Ga. Aug 24, 2010).

[5] I previously wrote about the Troy Davis eyewitness evidence in a short piece in Slate. See Brandon L. Garrett, “Eyes on an Execution,” Slate, September 20, 2011.

[6] Brandon L. Garrett, Convicting the Innocent: Where Criminal Prosecutions Go Wrong (Harvard University Press 2011).

[7] Baze v. Rees, 553 U.S. 35, 85-86 (2008) (Stevens, J. dissenting).

[8] U.S. v. Quinones, 196 F.Supp.2d 416, 420 (S.D.N.Y. 2002) rev’d U.S. v. Quinones, 313 F.3d 49 (2nd Cir. 2002).

[9] Kansas v. Marsh, 548 U.S. 163, 198 (2006) (Scalia, J. concurring).

[10] D. Michael Risinger, Innocents Convicted: An Empirically Justified Factual Wrongful Conviction Rate, 97 J. Crim. L. & Criminology 761 (2007).

[11] Samuel R. Gross & Barbara O’Brien, Frequency and Predictors of False Conviction: Why We Know So Little, and New Data from Capital Cases, 5 J. Empirical Legal Stud. 927 (2008).

[12] Frank Green, Williamsburg DNA Case Raises Question of Effort, Richmond Times-Dispatch, Feb. 5, 2012.

[13] Kansas v. Marsh, 548 U.S. at 191 (Scalia, J. concurring).

[14] MD. Crim. Law §2-202(a)(3).

Also from This Issue

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