Study suggests that 4% of the people we put on death row are innocent

Penn State

How well does the US justice system work? Given that many states still carry out the death penalty, it's a rather significant question.

Some biostatisticians have teamed up with lawyers in an attempt to provide a scientific answer to the question. Based on their figures, at least 4.1 percent of the individuals sentenced to death will eventually be exonerated. Given the high level of scrutiny that capital cases are subjected to, the authors conclude that the percentage of innocents stuck with life sentences is even higher.

The study seems to have been inspired in part by a comment from US Supreme Court Justice Antonin Scalia, who once claimed that US Courts have "a success rate of 99.973 percent." This, the authors say, is ludicrous. "In fact, the claim is silly," they write. "Scalia’s ratio is derived by taking the number of known exonerations at the time, which were limited almost entirely to a small subset of murder and rape cases, using it as a measure of all false convictions (known and unknown), and dividing it by the number of all felony convictions for all crimes, from drug possession and burglary to car theft and income tax evasion."