The threat of a mild punishment imposed reliably and immediately has a much greater deterrent effect than the threat of a severe punishment that is delayed and uncertain.A state trial judge in Hawaii, was frustrated with the cases on his docket. Nearly half of the people appearing before him were convicted offenders with drug problems who had been sentenced to probation rather than prison and then repeatedly violated the terms of that probation by missing appointments or testing positive for drugs. Whether out of neglect or leniency, probation officers would tend to overlook a probationer’s first 5 or 10 violations, giving the offender the impression that he could ignore the rules. But eventually, the officers would get fed up and recommend that Alm revoke probation and send the offender to jail to serve out his sentence. That struck Alm as too harsh, but the alternative — winking at probation violations — struck him as too soft. “I thought, This is crazy, this is a crazy way to change people’s behavior,” he told me recently. So Alm decided to try something different. He reasoned that if the offenders knew that a probation violation would lead immediately to some certain punishment, they might shape up. “I thought, What did I do when my son was young?” he recalled. “If he misbehaved, I talked to him and warned him, and if he disregarded the warning, I gave him some kind of consequence right away.” Working with U.S. marshals and local police, Alm arranged for a new procedure: if offenders tested positive for drugs or missed an appointment, they would be arrested within hours and most would have a hearing within 72 hours. Those who were found to have violated probation would be quickly sentenced to a short jail term proportionate to the severity of the violation — typically a few days.