Sure, and the same juries that let those guilty men walk will put innocent men in prison. Simple example: A guy in my city got put away for 20 years for molesting his neighbour's kid. 20 years later she comes forward and admits she made the entire thing up because she was having crippling mental health problems from the guilt of knowing he was locked up and she could set him free at any time. Turns out she did it because the families were feuding. There was no evidence he did it (other than her story) but he was put away anyhow. If we was dead we probably never would have heard the truth. Something like that happening should result in an enquiry and changes to the rules of evidence to ensure it never happens again. It should be considered impossible, but instead we're constantly looking for new ways to make it easier to convict with less and less evidence.