The young man enters the traffic court. In minutes he takes his turn before the judge. "Says here you were doing forty-five-miles-an-hour in a twenty-five-mile-an-hour zone. Guilty or not guilty? How do you plead?"

"Guilty, your Honor," comes the reply.

"Not guilty," bellows the judge. "Next case."

Such an exchange seems highly unlikely in most courts of law. Most judges would simply slap a fine on you.

Yet there is a system of justice which delivers "Not guilty" verdicts on people who do wrong. This …