An experimental court taking on some of the toughest addiction-driven criminals has cut reoffending rates and saved millions of dollars in prison costs.
So far 70 offenders have been all the way through the first Drug Treatment Court, and only a small number have returned to prison.
The court is three years into a five-year pilot.
Judge Lisa Tremewan, who helped set it up, told Nine to Noon the court was expensive to run, with its intensive treatment and drug-testing regime lasting months.
All of the offenders had been facing prison sentences, and avoiding those had saved $5.5 million in prison costs.
The amount of drug-taking had also been cut back, with most offenders completing a course to address their criminal thinking.
The court's success is gaining international attention, with Judge Tremewan telling 70 French judges about it in Paris recently.
Judge Tremewan said she hoped it would carry on and that new versions would be set up outside Auckland.
The United States, where the first drug courts were set up in 1989, now has 3000 of them.