Incorrect: Japan has a 99.95% conviction rate for cases that go to trial. This is partly achieved by lengthy pretrial detention determined to extract confessions out of people, but equally importantly by not prosecuting any cases that are less than watertight (read: the culprit has already confessed).
>>themat+(OP)
This raises a good point. A just state should be efficient at identifying crimes; an unjust state can charge suspects who will never be convicted, or harass them without charging them.