Easy -- No one is ever punished for anything and crime gets to the point that society crumbles, because as humans we cannot enact a justice system that does not occasionally punish innocent people.
Slightly less easy, but closer to current reality: For "don't knowingly punish innocent people" -- enact a justice system that is terrible at fact finding (or has gross bureaucratic and procedural inefficiencies), so that you punish a lot of innocent people but never do so knowingly.
Easy again: For "don't punish innocent people, knowingly or otherwise -- you have no criminal justice system that is workable within these constraints in the real world.
