Successful efforts to improve the state's criminal justice system seem to be few and far between.

But the evidence is building that at least one program — the Hawai'i's Opportunity Probation with Enforcement, or HOPE — is generating impressive results.

This suggests a way forward for state policymakers struggling with a too-high recidivism rate, too many people in prison and too few options to get probationers back into a normal, productive life.

HOPE, the brainchild of Circuit Court Judge Steven Alm, uses swift, strict (as in jail time), but short-term punishment for probation violators, even for first-time offenses.

Preliminary results of a study, presented to a Pew Charitable Trusts conference on Thursday, are encouraging: An 85 percent reduction in missed appointments, and a 91 percent reduction in those testing positive for drugs. HOPE participants also had far lower arrest rates and probation revocations than the control group.

The study, by researchers at UCLA and Pepperdine University, will be completed at the end of the year.

If the final results show that HOPE can reduce the number of new crimes committed by probationers, then it's reasonable to ask: How do we expand HOPE's reach, and how do we pay for it?

It would be a good investment: Helping someone stay out of prison and live a productive life always is.