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April 28, 2014
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At least one in 25 death-sentenced people are innocent, study claims
April 28, 2014
Special to World
A new study estimates that at least one in 25 people sentenced to death in the United States are innocent.
Researcher Samuel Gross of University of Michigan Law School and colleagues published the analysis in this week’s early online edition of the research journal
Proceedings of the National Academy of Sciences.
Some researchers have held that the rate of false convictions is unknowable since,
if there were some systematic way to determine conviction
accuracy, errors wouldn’t occur in the first place. In the absence of
hard data, some have claimed the false-conviction rate is almost zero.
Gross and colleagues focused on death sentences, which have a far higher exoneration rate than other sentences.
“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,” they wrote. “This makes it
possible to use data on death row exonerations to estimate the
overall rate of false conviction among death sentences.”
Noting that most death-sentenced defendants are re-sentenced to life in prison and don’t stay on death row, the researchers analyzed exonerations from 1973, when the
United States established the death penalty in its modern form, to 2004.
Their data came from the Department of Justice and the Death Penalty Information Center, a nonprofit that tracks exonerations among capital defendants.
In terms of actual exonerations, “2.3% of all death sentences imposed from 1973 through 1989 resulted in
exoneration by the end of 2004,” the researchers wrote. But the
exoneration rate becomes much lower for defendants re-sentenced
to life in prison, they noted. Using “survival analysis,” a technique
from epidemiology, they estimated that if all death-sentenced defendants
had stayed under execution threat for 21 years, at least 4.1 percent would
have been exonerated.
Of course, they added, the study must contain errors—such as by not
accounting for the exonerations, unknown in number, that must
also be erroneous. But Gross and colleagues claimed their work makes “conservative
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A new study estimates that at least one in 25 people sentenced to death in the Un ited States are innocent.
Resarcher Samuel Gross of Uni vers ity of Michigan Law School and colleagues published the analysis in this week’s ear ly online edition of the research journal PNAS.
Some researchers have held that the rate of false convictions is un knowable since such errors often remain un noticed forever. Gross and colleagues focused on death sentences, which are associated with a far higher exoner ation rate than other sentences.
Noting that most death-sentenced defendants are resentenced to life in prison and don’t stay on death row, the researchers analyzed exoner ations from 1973, when the modern form of the death penalty was established in the Un ited States, to 2004.
Their data came from the Department of Justice and the Death Penalty Inform ation Center, a nonprofit that tracks exoner ations among capital defendants.
The authors found that the high exoner ation rate applies on ly while the defendants remain un der threat of execution. Using “survival analysis,” a technique in epidemiology, they estimated that if all death-sentenced defendants were to stay un der execution threat indefinitely, at least 4.1% would be exonerated.