Tuesday, October 02, 2012

DNA exonerates 300 but can't clear most innocents

The Washington Post's coverage of the 300th DNA exoneration nationally - that of Damon Thibodeaux, who was released last week from Louisiana's death row - made an astute observation about the limits of DNA evidence to rectify false convictions ("Louisiana death row inmate Damon Thibodeau exonerated with DNA evidence," Sept. 28):
The Thibodeaux case marks a dramatic mathematical milestone in the use of DNA in law enforcement, but it also signals the opening of a new, more complex phase in the use of such material in attempts to right the course of justice.

When DNA testing was first introduced in the late 1980s, the revolutionary new techniques shattered a widely held view in law enforcement and the public that American courts rarely convicted the innocent. Since then, high-profile exonerations and the increasingly common reliance on such testing have led many to believe that DNA can resolve doubts about almost any questionable conviction.

It’s now clear, however, that there is no DNA evidence in the vast majority of cases. In the first 15 years of DNA testing, almost all exonerations fit a basic pattern in which the defendant was accused of rape, or both rape and murder — because sexual assaults are the crimes in which DNA is most likely to be recovered. Between 1989 and the end of 2007, a total of 214 people were cleared using DNA evidence. In all but 14 cases — more than 93 percent — the alleged crime involved a sexual assault of some kind, according to a review by The Washington Post.

In hindsight, those straightforward, obvious miscarriages of justice were the low-hanging fruit of DNA exonerations. Now their numbers are declining. In their place are convictions such as Thibodeaux’s, in which serious doubts have been raised but little clear DNA or other scientific forensic evidence exists to conclusively prove guilt or innocence. In Thibodeaux’s case, the absence of any incriminating DNA evidence became as powerful an argument for his innocence as any other element of the case.
Of 83 exonerations in the past five years, more than 15 percent didn’t involve rape. As many as a quarter of the cases involved a false confession, in which one or more defendants admitted to the crime under interrogation.

Samuel Gross, an author of a report by the recently created National Registry of Exonerations at the University of Michigan, calculated that based on the proven rate of exonerations among death-row prisoners in the past two decades, U.S. courts appear to have an error rate in capital cases of between 2.5 percent and 4 percent. In June, researchers examining biological evidence from hundreds of Virginia rape convictions between 1973 and 1987 determined that new DNA testing appeared to exonerate convicted defendants in 8 percent to 15 percent of cases.
Applied against the approximately 140,000 prisoners on death row or serving life sentences in the United States, the findings suggest that many thousands of innocent individuals could be in prison for crimes they didn’t commit.

But the odds that many of those convicts will ever be able to prove their innocence through the existing systems of appeals are remote, given the lack of DNA evidence in the majority of cases.
Those observations are spot on, highlighting concerns this blog has been raising now for several years that focusing on DNA exonerations ignores most innocence cases. There have been several efforts to estimate rates of false convictions, ranging from a low of .75% (from an officer at the national District Attorneys association) up to 1.5%, to 2.3%, to 3.3% or even higher. A 2003 survey (pdf) of criminal justice practitioners estimating the proportion of "false positives" found that "Prosecutors and police perceive the least error (1/2-1%), while defense attorneys perceive the most error (4-5%). Judges perceive the national error rate to be between 1 and 3 percent."

If your correspondent were pressed on the point, my own guesstimate at the right proportion would fall between one and two percent - probably on the upper end of that range. Higher estimates tend to be based on capital murder and rape convictions, which for a variety of reasons likely see greater proportions of false convictions because of tremendous pressure to clear cases and lower standards of evidence required to convict, particularly for sexual assault, where a single eyewitness can generally be sufficient to secure a conviction. OTOH, most innocence estimates fail to take into account wrongful convictions arising the drug war, which in Texas, just taking into account the Tulia, Hearne and the Dallas fake-drug scandals, actually outnumber DNA exonerations.

Obviously, even the lowest of those estimates far exceeds the number of DNA exonerations. If just .75% of inmates in Texas prisons are actually innocent, that would translate to nearly 1,200 people currently incarcerated in Texas prisons for crimes they did not commit, though the real number could obviously be even higher. In the overwhelming majority of those cases there is and never will be DNA evidence available to prove their innocence.

For that reason, DNA exonerations should be viewed as a sample, the way pollsters judge public opinion by sampling the views of a much smaller group. Like opinion polls, conclusions drawn from such a sample may suffer from a margin of error, but in general they allow us a rare window into the causes of false convictions that was not previously available.

All that to say, while the 300th DNA exoneration is cause for celebration - particularly for Mr. Thibodeaux - it also reminds us that the underlying causes of false convictions remain and cannot be remedied solely by DNA.


Anonymous said...

Grits, is there research that identifies the number of inmates convicted in cases where identity was seriously disputed or was in question. Those are obviously the cases where DNA evidence would be the most probative. Just based upon my own anecdotal observations, I would be willing to estimate that in at least 90% of the felony prosecutions in Texas, the identity of the accused in not seriously disputed. This would certainly be the case in most dope cases where the defendant is caught red-handed, Felony Driving While Intoxicated, and most crimes of violence where the defendant and the victim are acquainted or related. I just don't think on a percentage basis, there are that many "whodunits."

Gritsforbreakfast said...

I haven't seen that research if it exists, 9:21, but even in some of the cases you cite - like dope cases - there are lying snitches, for example, who cause false convictions as with the Dallas fake drug scandal. There are also cases - like the four gals in San Antonio accused of child sex assault - where identity isn't an issue but unreliable witnesses and/or flawed forensics may still result in false convictions, which don't only occur in "whodunnits."

Anonymous said...

I'm sure in nearly every kind of case, you might be able to find examples of mistakes or injustices. The main problem with the Dallas fake drug scandal that you allude to, for example, was sheetrock and unscrupulous officers. Neither the identities of the suspects, or their propensity to engage in narcotics transactions, was never really in question.

On the other hand, in the murder and rape cases where the identity of the suspect is legitimately in disputed, we know from fairly reliable data that there has been a demonstrated and statistically significant error rate in the reliability of eyewitness identifications. DNA evidence has gone a long way toward remediating that problem.

But I don't think you can necessarily assume that just because there have been a number of exonerations in those "whodunit" cases, that there will be the same percentage of innocents in other types of cases where the guilt of the defendant is pretty much cut and dried.

Anonymous said...

"cases where the guilt of the defendant is pretty much cut and dried."

I would bet that in every one of the exoneration cases there were prosecutors and/or law enforcement that were convinced "guilt of the defendant [was] pretty much cut and dried."

Anonymous said...

If there were a way to tell, absolutely without a doubt, when a person was lying, I think we'd see many many more exonerations than we have with DNA. I think many people would be shocked at how often witnesses, including law enforcement officers, lie. I think we would find that there are as many or more wrongful convictions in non-DNA cases as we've seen in DNA cases. One day, with the advances in neuroscience, we may have that technology. I predict the amount of dishonesty in the criminal justice system that will be revealed will be shocking.

Gritsforbreakfast said...

10:40, I get your point, but you're overlooking Tulia, Hearne and the Dallas fake drug scandal, which resulted in more wrongful convictions together than ALL Texas' DNA exonerations so far. It's false to say that in the Dallas fake drug scandal the defendants' "propensity to engage in narcotics transactions, was never really in question." That's an untruth. Those folks were set up and there's no evidence at all besides testimony from proven liars any of them engaged in drug dealing. Anyway, why do you pretend that that's the only case where one might find "unscrupulous officers"? Are you really that naive, or just emboldened by the shield of anonymity?

Finally, it borders on disingenuous to say that on eyewitness ID, for example, "DNA evidence has gone a long way toward remediating that problem." Biological evidence only exists in about 10% of violent crimes. For the other 90%, the problem remains. And even the new eyeID procedures only reduce error rates to still-high levels, they doesn't eliminate the problem. Wishful thinking won't make the problem of convicting innocent people go away.

Noname for good reasons said...

When I spent a summer working for a federal judge, an AUSA did part of our training. We watched part of a drug trial where a visitor to the home of his sister was charged with possession of crack that actually belonged to her boyfriend. The kid (17 yo) was asleep on the couch and the only person in the apartment, so was charged with possession when the drugs were found in a box on top of the frig. Convicted based on testimony of the officer, who clearly was not telling the truth. The boyfriend was known to deal, the kid had been in town less than 24 hours, to look at a college, when busted.

The AUSA told us that in every trial, the testifying officer has no real memory of the events, and cannot, given the number of cases that intervene. So they rely on the notes and reports, which may have errors, and those get compounded in created recollections of what actually happened.

Anonymous said...

The police lie routinely. There has been plenty written on it. Most articles reference the Slobogen paper:


Everybody realizes the police lie on search and siezure. However if this is the everyday accepted practice where is the line? What stops them from lying about facts related to actual inocense. There are no doubt millions of people in jail that are legally not guilty if not legally innocent.

The point made in 1:34 about police not recalling details is probably accurate. This is an argument for faster resoultuion of cases and/or more documentation.

This epidemic of perjury, and court's acceptance of it far overshadows some of the other problems causing false convictions.

Anonymous said...

@1:34...How did the defendant get convicted if the officer was "clearly not telling the truth?"

And Grits, I'm really not trying to difficult here or a smartass. I really want you to help me understand here why you believe it's appropriate to attempt to extrapolate a percentage of wrongfully convicted defendants across the entire spectrum of all the different types of criminal cases from the number of DNA exonerations.

I just don't think you can assume there's the same level of risk of wrongful conviction when you compare a stranger on stranger rape case to, let's say, felony DWI's (which in most instances today have a patrol car video as well as a blood test). And that's not even mentioning the percentage of cases where the defendants confessed and pled guilty (and I know that will open up a whole other topic of discussion).

My point here is this: DNA evidence has been helpful in clearing certain types of defendants in certain types of cases. The facts and dynamics of those cases are all fairly common, i.e., case rested primarily upon the identification of the defendant by the victim or witnesses who were not previously acquainted with the defendant; and there was some biological material still available to test which cleared the defendant at some later date.

Stated differently, I don't think you can necessarily propose that because in X% of the stranger rape cases there was flawed eyewitness testimony, the exact same percentage of defedants convicted in drug cases are wrongfully convicted due to police officer misconduct. I don't think you're comparing apples to apples here.

Incidentally, in regard to police officer misconduct, has there been any study on the number of arrests and convictions stemming from traffic stops following the proliferation of dash mounted video cameras? I know at the time dash mounted video cameras first began to become common, there was this thought or belief on the part of some that the cameras would reveal this whole new level of police officer misconduct and abuses. I don't think that's proven to be the case at all. Instead, the videos seem to have done more to provide more evidence of guilt than they've helped criminal defendants.

Anonymous said...

"belief on the part of some that the cameras would reveal this whole new level of police officer misconduct and abuses."

Look around - it seems to me that this belief has been validated. We've seen video after video of misconduct. And, this doesn't include cases where the officers have turned their mics off or even turned the camera off sometimes claiming it "malfunctioned."

If anything, the use of cameras has shown a lot of people who wouldn't have believed it before just how common misconduct is.

Maybe its all in your perspective, I dont' know.

Anonymous said...

I'm going to go out on a limb here and make a statement:

I suspect that, if we could detect them all (which now we can only detect a small fraction), we would find that the number of wrongful convictions due to prosecutorial and police misconduct far outnumbers the number due to faulty eyewitness identification.

Gritsforbreakfast said...

2:07, no study I know of re: police dashcams, but from what I've seen they've done both - shown evidence of offender guilt and also proven misconduct - though one finds sometimes when there are misconduct allegations the cameras mysteriously malfunctioned or were pointed the wrong direction. And having lobbied for that bill when it passed (over police union objections) in 2001, I can assure you that we ALWAYS claimed it would catch more crooks than bad cops. That's not news, it's the law working like it's supposed to. The police unions opposed it because they thought the marginal increase in good arrests wasn't worth even the slightest increase in proven allegations of police misconduct.

As to your point about extrapolation, the survey of practitioners cited wasn't limited to the types of cases you describe, and judges put the false positive rate system-wide at 1-3%. To me, the existence of significant numbers of false convictions in the drug war (where dashcams generally offer no protection, e.g., from a lying snitch) means your assumption that this is only a problem with whodunnits is misguided.

Certainly rape cases are different than theft or drug cases, but do you fantasize no one has ever been falsely accused of theft? Or that the Dallas fake-drug scandal was a one-off? Do you really believe eyewitness errors are the only type out there? Even among DNA exonerees there are a litany of other causes of false convictions. That's simply not the only source of error in the system.

Thomas R. Griffith said...

Hey Grits,

IMHO, we've had the opportunity of a lifetime to witness 300 DNA exonerations (so far) solely due to one constant theme. That being the concentration on this sub group of humans having wrongful conviction claims based on 'it' by the Innocence Network, Senators, State Reps. and those that mirrored it.

Yes, hell yes, the tired ol mantra (it’s better than nothing) has run its course & yes some take non-DNA claims with strings (must have exhausted all appeals) attached” that ignores the un-appealable cases..... But mark my words (my name is right up there as always) -
*The very moment that GFB posts an article announcing that the Governor has: created, implemented & is currently operating the very first - “Post Conviction Inspection & Integrity Unit of Texas” program, the overwhelming numbers of non-DNA (VOTS) victims’ of the system will force state wide judicial reforms (focusing on ending plea bargaining abuses a leading cause of wrongfully convicting one’s self to avoid 99 years - / +) as the voters and taxpayers are forced to wake up after decades of suffering from denial dieses.

'All' claims will be vetted by the State of Texas if we the people demand the state to do what projects' can't and don't. Folks, you can continue to squint as you pay in to the account set up for a handpicked group of VOTS & let the limited do their appreciated piecemeal work or you can do your part by checking the link below and consider putting your name on it and assisting.

Bitchin to Grits in the shadows about percentages and studies is just plain goofy and won’t change one damn thing unless it's accompanied by positive actions (BTW, sorry Comments’ don’t count). Thanks.