When innocence is not enough to get you out of prison

This is horrifying:

If you are a wrongfully convicted man or woman in this country, it is extremely difficult—if not outright impossible—to win your case by advancing the simple argument that you are innocent. Sounds crazy, right? But it's true. The Supreme Court has repeatedly declined to hold that the federal Constitution allows for so-called freestanding claims of innocence, that is, the right to be let out of prison simply because you didn't do it, without any other "technical" violation to back up your argument. In the United States, the inmate who raises a compelling case of innocence after a constitutionally proper trial may well be doomed.

Source: Slate.com, March 11, 2015.