The state can do that.

Parolees may not live behind bars, but they are far from free. Their parole officers have enormous power to dictate whom they can see, where they can go, and whether they are allowed to do perfectly legal things like have a beer. Breaking those rules can land a parolee back in jail — the decision is up to the parole officer.

In some ways, Mr. Brantley was fortunate. He faced a system far less punitive than it might have been a few years earlier, thanks to Connecticut’s efforts to give parolees more chances to succeed. When Mr. Brantley failed a drug test, he wasn’t sent back to prison. Instead, he was ordered into treatment.

But addiction is only one of the many challenges faced by those getting out. As prison populations drop, the number of parolees is increasing — people with layer upon layer of disadvantages that often date back to early childhood. For more than a year, “Frontline” and The New York Times followed newly released prisoners as they tried to find homes and jobs, reconnect with loved ones and avoid temptation, sometimes discovering that the system created to help them can also hold them back.

One of them could not buy his daughter the Christmas present she wanted because the halfway house controlled his spending; another, living in her own apartment, was told her boyfriend could not spend the night. For their part, parole officers were making difficult calls about the best interests of their charges, while navigating safety rules such as the one that affected Mr. Brantley: no contact between parolees and their past victims.