Right now, there are more than 3,100 inmates on death row, and more than 60% are members of racial or ethnic minorities. Over time, Supreme Court Justices have fine-tuned the circumstances under which the death penalty may still apply, but no set of laws or jurisprudence can undo wrongful executions — or, it seems, completely prevent them.

According to journalists Martin Clancy and Tim O’Brien, authors of Murder at the Supreme Court and Bill’s guests this weekend, at least 18 inmates were released from death row in recent years because DNA evidence proved their innocence. These cases are among more than 140 death penalty exonerations over the last three decades.

Watch an extended preview of the show in which Clancy and O’Brien make the case that — for the poor in America — justice is still unaffordable.