Sheriffs of New England, you’ve got mail.

The American Civil Liberties Union chapters of Maine, Massachusetts and New Hampshire last week sent a letter to every sheriff’s office or jail asking them to offer medication-assisted treatment to incarcerated people with opioid use disorder.

The law enforcement officials should listen – and they have two very good reasons for doing so.

First and foremost, medication-assisted treatment, such as Suboxone and methadone, works; it reduces drug cravings and lowers drug sensitivity, and puts people with opioid use disorder on a path to stable living.

If it is not offered, people who were undergoing treatment before being incarcerated lose whatever gains they had made, and those who enter jail or prison untreated don’t get the help they need. Both undergo painful withdrawal that does nothing to address the factors behind their substance use.

And when the person is eventually released, they are let back out into the world untreated, and at a higher risk of overdose and re-offending.

In 2016, Rhode Island began screening all inmates for substance use disorder, then providing medication-assisted treatment. A subsequent study found overdose deaths upon release fell 61 percent in a year. At a time when overdose deaths among the general population were spiking elsewhere, Rhode Island’s fell 12 percent, largely thanks to the new policy.

Every jail or prison should want such results.

The second reason they should offer medication-assisted treatment is that it is the law. Federal court rulings in Maine and Massachusetts have said that people are entitled to continued access to medication-assisted treatment for opioid use disorder while in custody, just as they would be entitled to treatment for any other illness.

In Maine, the decision meant a woman in Aroostook County wouldn’t lose the treatment that she credited with saving her life just because of a 40-day jail sentence. In her opinion, the judge in the case wrote that a “body of evidence has emerged that permitting MAT in correctional facilities offers substantial, and possibly essential, benefits to incarcerated people.”

(A few weeks before the decision, Gov. Mills lifted a ban on medication-assisted treatment in state prisons. Several jails in Maine also offer treatment.)

Incarceration is supposed to be an opportunity to turn one’s life around. Though it rarely lives up to that standard, it can in this case. Often, it is addiction itself, either directly or indirectly, that is the reason for incarceration. If nothing is done to address addiction during incarceration, then it will be difficult for the incarcerated person to change their behavior and build a better life.

No one is helped when proper addiction treatment is denied, and that goes double for people in jail or prison. If they are not offering it, corrections officials should follow the advice of ACLU, and get started.