NCPA - National Center for Policy Analysis


April 26, 2007

Much of the empirical confusion about wrongful conviction rates has been driven by histrionics over the death penalty.  Lost in the debate is any reliable data about the actual wrongful conviction rate, says Morris B. Hoffman, a Colorado district court judge and an adjunct professor of law at the University of Colorado.

But the innocence data can be mined for some approximations.  And those approximations suggest that the actual rate of wrongful convictions in the United States is vanishingly small:

  • In the first place, almost all criminal defendants plead guilty; the national plea bargaining rate is around 95 percent.
  • That means that even if juries get it right only 80 percent of the time (an assumption at which most sensible scholars would cringe), the overall post-trial wrongful conviction rate would still be only around 1 percent.

But the real wrongful conviction rate is almost certainly lower, and significantly so, says Morris.  Earlier this week the innocence project at Cardozo School of Law issued a press release celebrating the 200th person exonerated by DNA testing.  But in the 20 years innocence projects have been operating, there were roughly two million criminal trials in the United States.

  • Assuming as many as 25 percent of those trials resulted in acquittals (and ignoring, as the innocence merchants are wont to do, the problem of wrongful acquittals), the wrongful post-trial conviction rate is only 0.013 percent.
  • Since only 5 percent of cases are tried, that would place the overall wrongful conviction rate at around 0.00065 percent.

Of course, this is just a lower bound estimate, based on several admittedly questionable assumptions, including that the innocence-project data is representative, and that no innocent people plead guilty.  But even if this estimate is an order of magnitude or two low, it is still considerably less than the mythmakers would have us believe, says Hoffman.

Source: Morris B. Hoffman, "The 'Innocence' Myth," Wall Street Journal, April 26, 2007.

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