An innocent man in jail is the proof that the state has not the necessary foresight and capacity to rule fairly; it's an abuse of power in a way, and it takes away time of people's life, sometimes ruining many of their relationships and opportunities, and there's nothing that can fix that. An innocent person's life is ruined for nothing. Of course, a criminal on the street is dangerous, but the fact is, we have plenty of them already, and we'll never have them all. But it's many time a matter of time before they are caught. In the first case, the State committed an irreparable crime. In the second, it missed the opportunity to protect better, but it could be just a matter of time. Both are bad.