One of the problems facing those who believe that the problem of wrongful convictions is far deeper that statistics currently available would indicate, is the dearth of reliable longitudinal data.
However, a new study that involved the DNA testing of hundreds of old Virginia homicide and sexual assault cases supports the exoneration of at least 38 suspects, according to a study released Monday by a national policy group that examined the test results.
This study, conducted by researchers John Roman, Kelly Walsh, Pamela Lachman and Jennifer Yahner of the Urban Institute Policy Center, analyzed the results of new DNA testing of old physical evidence from 634 sexual assault and homicide cases that took place in Virginia between 1973 and 1987.
Their central question: “What proportion of convicted offenders in serious person crimes with retained forensic evidence could be exonerated if that evidence were DNA tested?”
This marked the first study of the effects of DNA testing on wrongful conviction in a large and approximately random sample of serious crime convictions.
The study found that in five percent of homicide and sexual assault cases DNA testing eliminated the convicted offender as the source of incriminating physical evidence.
When sexual assault convictions were isolated, DNA testing eliminated between 8 and 15 percent of convicted offenders and supported exoneration.
Past estimates generally put the rate of wrongful conviction at or less than three percent.
These new figures are, in fact, staggering.
“I believe that there’s nothing about the Virginia situation that is much different from what was going on across much of the United States at that time,” said John Roman of the Urban Institute. “I think that states have a responsibility to take these findings seriously in other places and investigate other cases that they have where they have retained evidence, because chances are they’re going to find far more wrongfully convicted people than they would have anticipated before this study.”
Mr. Roman believes there are “dozens, if not hundreds, of people who were convicted erroneously; dozens, if not hundreds, of people who were not convicted of a crime they committed who may have gone on to commit new crimes; and there were dozens, if not hundreds, of people who thought they had justice as a victim of a horrible crime who didn’t.”
There were some limitations to their findings. One of the major ones is that “in two-thirds of the convictions the DNA analysis did not produce a DNA profile or no forensic determinations about wrongful conviction could be made.”
Because of the nature of the crimes, DNA evidence is more likely to yield “determinate results when compared to convictions for nonsexual assault homicide, simply because of the presence of a victim or suspect physical evidence recovery kit (PERK), which often yielded a DNA profile.”
“Thus, we cannot interpolate from sexual assault convictions with determinate results to nonsexual assault homicide convictions with indeterminate results,” they write. “These two limitations have particularly important impacts on the way in which we estimate the rate of wrongful conviction.”
There are two types of wrongful convictions, though most work focuses on the former, where the person convicted is factually innocent of the charges as opposed to procedural error that violated the convicted individual’s constitutional rights.
The researches in this case focus on DNA evidence demonstrating factual innocence as DNA testing cannot be used to detect erroneous convictions due to reversible procedural errors.
Most studies previously put the upper bound on the rate of wrongful convictions between 3 percent and 5 percent.
The researchers argue, “The data set in our study is better suited to determine rates of wrongful convictions than previous works. All cases in this study were convictions for serious person crimes, from a single time frame, where biological evidence was collected and tested in the original investigation.”
“Until this study, previous research on wrongful convictions has been based on data known only for cases in which the convicted offender (or others on his/her behalf) actively pursued exoneration,” they write.
Previous studies have found that minorities were overrepresented among exonerated offenders with false eyewitness testimony, false confessions, informant testimony, and faulty forensic evidence identified as the leading causes of wrongful convictions.
This would appear to be one of the first truly scientific studies, where the researchers used basic techniques of random sampling and blind testing of evidence to determine a rate of wrongful convictions.
Still, we believe that these results may still underestimate the true number of wrongful convictions. After all, physical evidence and DNA enter into play in only a small number of cases.
Determinate results even in this study were not obtained from DNA testing in two-thirds of the convictions.
In addition, they argue their “biggest data limitation is omitted variable bias, primarily the lack of court data. We believe that our analysis would have been greatly improved by additional court variables (particularly method of conviction (jury/bench trial or guilty plea)), type of defense attorney (court-appointed or retained), whether the offender confessed or gave incriminating statements, victim and eyewitness identification, offender’s prior record and mental health problems, and results from those appeals and would have allowed us to test theories put forth in prior studies, particularly about the impact of witness identification, trial type, and confessions on wrongful conviction.”
They also noted that the physical evidence was very old and in a number cases already subjected to forensic testing.
They conclude two findings that are not in dispute.
“In convictions from VA between 1973 and 1987 where evidence was retained in a sample of homicides and sexual assault cases that resulted in a conviction, the suspect is eliminated as a contributor for a probative evidence item, and that is supportive of exoneration in 5 percent of convictions,” they find.
Second, “we find that in convictions from VA between 1973 and 1987 where evidence was retained in an unbiased sample of convictions for sexual assault cases, the convicted offender is eliminated as a contributor for a probative evidence item, and that is supportive of exoneration in between 8 and 15 percent of convictions.”
—David M. Greenwald reporting
“Still we believe that these results may still underestimate the true number of wrongful convictions. After all physical evidence and DNA enter into play in only a small number of cases.”
Staggering figures, indeed. Terrifying, in fact. Any report on what’s become those improperly convicted? Since two-thirds of the samples produced no result, that means the 38 “exonerated” came from only about 211 cases, a rate much higher than the five per cent, correct?
“All cases in this study were convictions for serious person crimes, from a single time frame, where biological evidence was collected and tested in the original investigation.”
Tested for DNA match? In 1973?
“Still we believe that these results may still underestimate the true number of wrongful convictions. After all physical evidence and DNA enter into play in only a small number of cases.”
Maybe so. The good news is that DNA testing now is commonplace in investigations of such crimes and is excluding suspects who might have been prosecuted–and, apparently, convicted–in earlier days. (Unless investigators and prosecutors would illegally withhold such results…but, don’t let me get you started….)
Thanks for covering this scary finding. Please provide a link.
[quote]When sexual assault convictions were isolated, DNA testing eliminated between 8 and 15 percent of convicted offenders and supported exoneration.[/quote]
Supported exoneration? Just because DNA testing did not support conviction does not mean the person did not commit the crime. For instance, in rape cases, it is not unknown for the criminal to use a condom so that he will not be identified through DNA testing…
Elaine, it sounds as though this study excluded those who were convicted. Otherwise, how would the findings “support exoneration”? I guess, using your example, if two perps raped, use of a condom just by the one who got convicted could result in the situation you describe.
“it sounds as though this study excluded those who were convicted. “
On the contrary, the study looked at the cases without regard to whether the individual was convicted and of its strengths was that it showed both those that were confirmed and those excluded by DNA testing.
Link to study: [url]http://www.urban.org/publications/412589.html[/url]
Since I have no idea what I was trying to say, I’ll give up until it comes to me.
But, your comment about the study evaluating without regard to whether there was a conviction needs some more explanation since it seems a little nonsensical too. Wasn’t it all about wrongful convictions? I’ll get back to you.
Does the study review the trials of each of these cases to determine if the case presented at trial supported the conviction?
Just saying: It was about determining what the rate of wrongful convictions was. They did that by looking at x-number of old cases with DNA evidence that is now available.
Mr. Obvious: I wrote: they argue their “biggest data limitation is omitted variable bias, primarily the lack of court data. We believe that our analysis would have been greatly improved by additional court variables (particularly method of conviction (jury/bench trial or guilty plea)), type of defense attorney (court-appointed or retained), whether the offender confessed or gave incriminating statements, victim and eyewitness identification, offender’s prior record and mental health problems, and results from those appeals and would have allowed us to test theories put forth in prior studies, particularly about the impact of witness identification, trial type, and confessions on wrongful conviction.”
I hope that people will realize that this DNA testing is only available in a small minority of cases. There are many wrongful convictions that cannot be uncovered this way. I am thrilled that these studies are being done so people will understand that wrongful convictions happen more than people had realized.
Unfortunately, in Ajay Dev’s case there was no rape so there is no DNA evidence to exonerate him. He has to fight it out in the appellate courts.
Hopefully uncovering how these wrongful convictions happen will eliminate the horror for others like Ajay who have been wrongfully convicted.
[quote]I hope that people will realize that this DNA testing is only available in a small minority of cases. There are many wrongful convictions that cannot be uncovered this way. I am thrilled that these studies are being done so people will understand that wrongful convictions happen more than people had realized. [/quote]
The problem is these types of studies are often flawed themselves. As I pointed out, just because a DNA test is not supportive of conviction, it is not necessarily supportive of exoneration. An example is rape cases where the perpetrator used a condom. The perpetrator committed the crime, yet a DNA test would not support conviction – but neither would it support exoneration.
I agree with your point that DNA testing is not involved in many cases, and so cannot be used as a tool for uncovering wrongful convictions. I would also concede there are wrongful convictions, and probably far more than are reported. However, I think money would be better spent correcting flaws we already know are inherent in the criminal justice system, e.g. more funding to public defenders, than to continue studies like these, to prove pretty much what we already know…
“The problem is these types of studies are often flawed themselves. As I pointed out, just because a DNA test is not supportive of conviction, it is not necessarily supportive of exoneration.”
Again, you don’t have to deal in hypotheticals here. In this study, they set the exoneration point at DNA evidence that excludes the defendant. In other words, they are not looking to question the the conviction, they are looking at evidence of factual innocence.