So, the prison system my stepson was in:
he was required to complete a program regarding drugs, addiction and rehabilitation, he could not be released with out completing this "modality" whatever that means.
Then he was on a work release program. He rode a bicycle to work 8 miles away (fitness!) and was urine tested upon return each afternoon.
He was released with the parole requirement of attending AA or NA, having a sponsor and reporting to his parole officer every month and subject to drug testing at any time.
When he got out, he was adamant that he would not return to prison and knew that if he violated he would serve at least the remainder of the original sentence.
He kept this frame of mind for 6 months or so, then began using again until it (crack) was using him.
The first time he violated, he got a stern lecture from the judge but also another chance.
The second time it was back to prison.
It sounds to me like the system gave him several good opportunties to get help and get and stay clean...but he had other plans.