[BluffTHIS!]

5% or so, although even as little as 3% might indicate serious flaws in the system. The cure though would be to fix the high error rate not let the guilty off easier. Similarly, although I don't believe the death penalty is appropriate in most cases, when people argue against it because it is applied unfairly because of racial bias, the solution is to apply it equally to similar situations not let more people off more easily.