Drug courts work. For years, Judge Robert Rancourt of Chisago County, a leader in the National Association of Drug Court Professionals, has come to the State Capitol with that message about the specialized courts that offer willing nonviolent drug offenders an alternative to prison. For years, skeptical legislators have asked him to produce Minnesota-specific numbers to prove his point.

Now he can. The results of a two-and-a-half-year study are in. They confirm what Rancourt and his drug court judicial counterparts have been saying: Intensive, treatment-centered drug court programs are more likely than are traditional correctional measures to improve lives marred by illicit drug use -- and they save taxpayers money to boot.

That's welcome and timely news. It runs counter to skepticism about government's ability to respond effectively to social problems. It speaks to the worth of a judicial branch that has come in for more than its share of politically motivated deprecation of late.

And it arms that branch with the best lobbying weapon -- hard data -- with which to fend off funding cuts when the next state budget squeeze comes. That's likely to be as soon as next year. (The report itself illustrates what tight money has meant for Minnesota's judiciary. It explains that it lacks a thorough cost-benefit analysis because the funding that would have made that possible was cut by the Legislature.)

The report compared the experiences of 535 drug court offenders with 644 offenders with similar profiles who did not opt for the drug court's regimen of treatment, intensive supervision, incentives for good behavior and sanctions for reoffending. Among the findings:

•Two and a half years after entering the program, 26 percent of the drug court cohort had been charged with a new offense, compared with 41 percent in the comparison group.

•Drug court participants spent fewer days incarcerated (jail plus prison) than does the comparison group, saving the state on average $3,200 per participant over two and a half years. But jail time is used as a drug court sanction, and in Hennepin County, that has meant more jail time for drug court participants than for the comparison cohort.

•More than half -- 54 percent -- of drug court participants finished the program, which typically involves about 18 months of frequent court appearances, random drug tests and completion of treatment. Sanctions including incarceration are quickly imposed if a participant is found to be using drugs.

•Drug court participants show gains in employment, educational achievement, home rental or ownership, and payment of child support over the run of the program. That in turn leads to reduced taxpayer costs, as formerly homeless and unemployed people become taxpayers.

Those results are positive. But they also show that even the intensive interaction with the criminal and social-services systems that drug courts provide isn't enough to bend every offender's life in a new direction. Chemical dependency is a formidable foe.

The new report acknowledges as much, and recommends possible program improvements. For example, it suggests that jail time may not be as effective as a sanction as once believed. More focus on program completion is in order, with new research to identify what works best to increase "graduation rates." Increasing the share of offenders willing to participate is another challenge.

"We can't build enough prisons to house everybody with a drug addiction issue," Judge Rancourt said this week. "In drug courts, more people who in the past were written off are being rehabilitated and are no longer a threat to their communities or themselves. That's the job that the courts are supposed to be doing."

Fifteen years after their Minnesota debut, drug courts are both a work in progress and a work producing progress.