By Stefan R. Underhill | The New York Times | January 23, 2016

In 2006, I sentenced a man to 18 years in prison. I have been wrestling with that decision ever since.

As a federal district judge, I’ve sentenced hundreds of people, but I’ve rarely agonized as much as I did over this man’s fate.

He was the enforcer for a brutal gang of drug dealers in Bridgeport, Conn., known as the Terminators, and had sold heroin, assaulted rival dealers and murdered a potential witness. But after a falling-out with the head of the gang, he turned over a stash house to the police and fled the state. When captured in 2001, he immediately confessed to the murder and later testified as a star witness for the prosecution.

Thus arose my problem: He had committed horrible crimes, but he also seemed to be making an unusually sincere effort to atone for them. So which man was I sentencing? The murderer or the remorseful cooperator?

The prosecutor rewarded his cooperation by filing a so-called 5K motion, which allowed me to ignore the mandatory life sentence he otherwise would have faced. Still, after weighing the seriousness of his crimes, I sentenced him to 18 years, which was more time than even the prosecutor wanted.

I gave a speech encouraging the defendant to make the most of his time in prison. He promised to work hard and ready himself to lead a productive life after his release. But nearly everyone I sentence says something similar.

In the years that followed, I often wondered whether his remorse was strong enough to overcome his past.

In 2012, I had the chance to find out. While attending a conference on sentencing issues, I learned that he was serving time in a prison nearby. I wanted to know whether he had become a better citizen or a better criminal. So I asked a prison staffer if I could meet with him in private.

That the warden felt no need to post a guard was my first clue that he had changed for the better. He was working in his first real job at the prison industries factory and had been promoted to supervisor. He showed me recommendations from prison employees for good jobs on the outside. He brought a folder full of certificates he had earned for attending classes. He talked lovingly about his girlfriend and daughter, with whom he planned to live as a family after his release.

The meeting made me proud of his accomplishments, but sad that I had not been more confident in him. He still had several years left on his sentence, but it was clear that he had served enough time.

After I returned to my office, I contacted the prosecutor and his lawyer and encouraged them to find a way to get him released early. But they told me there was no straightforward way to shorten a federal inmate’s sentence, even if prison officials acknowledge that more jail time is a waste of time and money. So he had to stay in prison, at an annual cost of $30,000 to taxpayers.

The tragedy of mass incarceration has recently focused much attention on the need to reform three-strikes laws, mandatory minimums and the federal-sentencing guidelines, which often direct judges to impose excessive sentences. We also need a mechanism for judges to re-evaluate the sentences they’ve imposed.

It’s true that federal prisoners can earn up to 15 percent off the length of their sentences if they stay out of trouble. But this doesn’t incentivize prisoners to take advantage of work or study opportunities.

Instead, Congress should enact legislation that would allow every sentenced defendant one opportunity to petition his sentencing court for a reduction based on extraordinarily good conduct and rehabilitation in prison.

This “second-look review” should be available only to prisoners who are supported by their wardens. To minimize the increased workload on busy federal judges, each prisoner should be allowed only a single opportunity to seek early release and do so only after serving at least half of the sentence imposed (or two-thirds of a mandatory minimum sentence).

Factors in support of an early release should include more than just clean disciplinary records in prison. Job readiness, success with drug treatment, completion of vocational and educational training and extraordinary family or health circumstances should count as well.

While the Bureau of Prisons has the authority under the existing “compassionate release” program to do much of what I advocate, that program has been used far too sparingly, in part because of bureaucratic hurdles. From 2008 to 2014, only 11 of the thousands of prisoners sentenced by federal courts in New York have been released under this program. Most of them were terminally ill. Compassionate release provides no realistic way out of prison. And prisoners with no reason to hope have little reason to reform.

I don’t advocate for a return to the flawed federal parole system that was essentially abolished in the 1980s. In that system, a judge who believed that a defendant should spend three years locked up would impose a nine-year sentence because parole was likely to be granted after he served one-third of it. But if that defendant’s parole was delayed or denied, the judge’s original intent was impeded. In contrast, my proposal would give the sentencing judge control. This makes sense because judges know whether a particular defendant got a break at sentencing or not and can best gauge the extent of positive change in a person.

The man I sentenced in 2006 will soon leave prison. Counting the time he served in custody before sentencing and time off for good behavior, he is scheduled to be released in April. In total, he will have served over 14 years. The last three years of that sentence, if not more, were a waste of time.

Upon his release, I will reach out to express my regret for rejecting the prosecutor’s request for leniency. And I will thank him for inciting my interest in this reform.

A “second look” to adjust sentences would give inmates an incentive to prepare themselves for productive lives on the outside, and allow judges like me to correct sentences that turn out, in hindsight, to be unnecessarily long. This would improve the fairness of our criminal justice system and increase the public’s confidence in our courts.

Stefan R. Underhill is a federal judge for the District of Connecticut.

This article was originally published in The New York Times Sunday Review.