Tuesday, April 29, 2014

Estimating innocence among defendants sentenced to death row

Lots of press today about a new article from the Proceedings of the National Academy of Sciences titled "Rate of false conviction of criminal defendants sentenced to death." The study's abstract reads:
The rate of erroneous conviction of innocent criminal defendants is often described as not merely unknown but unknowable. There is no systematic method to determine the accuracy of a criminal conviction; if there were, these errors would not occur in the first place. As a result, very few false convictions are ever discovered, and those that are discovered are not representative of the group as a whole. In the United States, however, a high proportion of false convictions that do come to light and produce exonerations are concentrated among the tiny minority of cases in which defendants are sentenced to death. This makes it possible to use data on death row exonerations to estimate the overall rate of false conviction among death sentences. The high rate of exoneration among death-sentenced defendants appears to be driven by the threat of execution, but most death-sentenced defendants are removed from death row and resentenced to life imprisonment, after which the likelihood of exoneration drops sharply. We use survival analysis to model this effect, and estimate that if all death-sentenced defendants remained under sentence of death indefinitely, at least 4.1% would be exonerated. We conclude that this is a conservative estimate of the proportion of false conviction among death sentences in the United States.
AP reports that, nationally, “From 1973 to 2004, 1.6 percent of those sentenced to death in the U.S. — 138 prisoners — were exonerated and released because of innocence.” This study attempts to extrapolate using statistical analysis how many other actually innocent defendants had their death sentence eliminated but were never formally exonerated, boosting the total to 4.1 percent. Noted AP, "The difficulty in identifying innocent inmates stems from the fact that more than 60 percent of prisoners in death penalty cases ultimately are removed from death row and resentenced to life imprisonment. Once that happens, their cases no longer receive the exhaustive reviews that the legal system provides for those on death row."

From what I know about rates of wrongful convictions, that doesn't sound unreasonable to me. I personally believe Texas has executed one or more innocent people over the last three decades, and numerous others have been exonerated after spending time on death row. Others, like Clarence Brandley and Kerry Max Cook, were freed from death row but never formerly exonerated. Indeed, it may be that high-profile death penalty cases have higher false conviction rates than others because of the intense pressure on prosecutors and judges to convict, though there are also plenty of false convictions in lesser cases. Either way, it's almost certain that false convictions in death penalty cases are more likely to be discovered after the fact because of the rigorous examination they receive during the habeas corpus process that almost never occurs for cases that end in a "mere" prison sentence.

That said, many death penalty abolitionists believe that these sorts of analyses may sway the public to oppose capital punishment, a position that simply isn't supported by the data. Among people who believe an innocent person has already been executed, a solid majority support capital punishment. Identifying people wrongfully sent to death row helps impress upon the public the import of rectifying flaws in the justice system that contribute to false convictions. But IMO, especially in Texas, it won't be any sort of silver bullet that convinces people to oppose the death penalty.


Jeff Gamso said...

It's not a silver bullet. But it's pretty clear that wrongful convictions have been among the factors that have led to reduced levels of support for the death penalty around the country (and probably even in Texas, though i haven't tried to track state-specific polling data).

On the other hand, I don't imagine this study will do much to convince anyone who doesn't already believe. Partly that's because it'll just be treated as some mushy social science mumbo jumbo. And partly because whatever you think of that 4.1%, it's impersonal.

There are no real silver bullets in this business, but if there's something close, it's the incontestably innocent guy who's been executed. Incontestably is the key there. Whatever we may believe, it doesn't quite apply to Todd Willingham or Carlos DeLuna or Leonel Herrera or the likely candidate of your choice.

Stalin said that the death of a million is a statistic. The death of an individual is a tragedy. Sad to say he was right about that.

Gritsforbreakfast said...

@Jeff Gamso, according to the last poll I saw, 74 percent of Texans strongly or somewhat support the death penalty, while 62 percent believe people are wrongly convicted and sentenced to death "occasionally" or a "great deal of the time." Most people who believe innocents have been executed still support the death penalty - that's true both in Texas and nationally.

While possible innocence may be "among the factors" leading to a recent decline in death sentences, it's not the main one nor typically a decisive one. When you hear prosecutors describe what motivates their decisions (e.g., see this case), it's more often cost, the length of the appellate process, and mitigation evidence that actually account for the decision not to seek death.

I know abolitionists would like to think that an "incontestably innocent guy who's been executed" would change public opinion, but hope is not a strategy and there's no valid evidence from public opinion polling that that factor changes many people's minds.

ckikerintulia said...

John Grisham has a novel, the title escapes me at the moment, about a guy sentenced to death. Post execution, he was incontrovertibly shown to be innocent. But it didn't change people's minds about the death penalty.

I would think what happened in Oklahoma last night might cause some on-the-fence people to jump off on the side of abolition of the death penalty. You try to execute a guy and botch the job. Then the guy has a heart attack and you try to resuscitate him, but fail. He's dead. Isn't that what the state wanted? Apparently not. Apparently Oklahoma was more fixed on killing the guy than on his being dead. He died, but dammit, we didn't get to kill him!

What's wrong with this picture?

Anonymous said...


An excellent yet frustratingly tragic book.

Grandmom said...

To pry people ( especially Texans) loose from their beliefs is next to impossible. They hold strong in spite of all contradictory evidence,fearful that changing their mind will somehow rob them of their independence and self-determination. But for the Supreme Court, Texas would still have segregation and the poll tax. Injustice is the issue that anti-death penalty groups must emphasize rather than innocent convictions; and, unfortunately, prosecutors will continue to oppose any criminal justice reform legislation which supports justice for all - innocent or guilty. They claim such legislation will "tie their hands".

Jeff Gamso said...

I don't think that factor exists, which complicates things. As I said, wrongful executions pretty demonstrably have some effect on national polling data, but you're right that it's a limited effect.

The incontestably innocent guy who's been killed hasn't been found. Will he end the death penalty when we find him? No. Will it make a significant difference? I think so. But as you say, that's speculation.

Cost, on the other hand, which is the worst reason to end the death penalty, does resonate - especially with legislators and (some) prosecutors.

Anonymous said...

The last time I checked with my abolitionist friends, they seemed to have a pretty realistic view of what would happen when it is demonstrated that an innocent person had been executed, despite all the procedural safeguards of the legal system. They don't view it as a silver bullet. There would be some people who would change their thinking. Not a lot. Maybe a few percent. But if support for the dp is at 75%, you aren't trying to convince 75%. You're trying to convince 26%. And a few percent would be a pretty big step toward that goal.

Gritsforbreakfast said...

Jeff Gamso writes, "Cost, on the other hand, which is the worst reason to end the death penalty, does resonate - especially with legislators and (some) prosecutors"

How is it the "worst reason to end the death penalty" if it resonates most with legislators, prosecutors and other decision makers? The reason abolitionists consistently fail IMHO is that they not only want people to oppose the death penalty, too many insist that others oppose it for the same reasons they do, valuing ideological purity over results.

Jeff Gamso said...

I used to be known in some abolitionist circles as the guy who objected to a single-minded focus on moral arguments. Whatever works, I said; let 100 flowers bloom I, I said (quoting Mao). I still think that.

Testifying in the Ohio Senate one day on a death-penalty related bill, I pointed out, in a side comment while answering a question, that with budgets tight they could save a ton of money by abolishing the death penalty. One of the senators said that if it was the right thing to do, money shouldn't matter.

I think he was right about that (although wrong about thinking it the right thing to do). Money is among the worst reasons to anything involving the criminal justice system which ought to be about what is and isn't right and fair and respecting of individual rights (along with, yes, I know I haven't mentioned it yet, attention to public safety).

That doesn't make it a bad argument. Obviously it has significant force with legislators and the public. And I care a lot less about motive in these things than in result. But even in the world of pure public policy reasons for abolition, there are better reasons to do it than that it might save some cash.