Any legal system is going to make mistakes, and people are going to be wrongfully convicted. The key is to ensure that there are procedures in place to minimize those mistakes and review processes in place to swiftly correct any mistakes that are made. So how well does the American legal system do at both of these?
In 2012 the Urban Institute finished a 6-year study of biological samples in criminal cases in Virginia that spanned 1973-1988. In some 638 cases, lab technicians preserved blood and other biological samples which could be tested for DNA evidence to see if there is a match with the individuals actually convicted of the crimes.
Of the 638 cases, the study found 37 cases “that might support exoneration and that certainly support further investigation.” If all 37 of those individuals are, in fact, not guilty of the crimes they were convicted of, that would yield a 6 percent wrongful conviction rate from those samples.
Except the wrongful conviction rate could be much higher. Of the 638 samples, 419 were classified as indeterminate–in some cases a DNA profile of the person convicted of the crime was unavailable or no usable DNA evidence was obtainable from the biological samples.
Of the remaining 219 samples, 149 samples implicated the person convicted, while 37 suggested the person convicted of the crime might be innocent. There were 33 cases where the DNA did not match the person convicted, but researchers concluded that this would not support exoneration or further investigation.
So of the cases where the researchers were actually able to reliably compare the preserved samples with the DNA of convicts, almost 17 percent of those findings led the researchers to conclude that the evidence “might support exoneration.”
That doesn’t exactly instill confidence in the efficacy of the American legal system.
The study was prompted by a smaller effort in 2005 in which testing biological samples ended up clearing two men who had been wrongly convicted of rape, and suggests there is something rotten at the core of how the criminal justice system operates.