RESIDENTS OF the District of Columbia deserve protection from the most violent criminals and to be confident those offenders receive prison sentences commensurate with the gravity of their crimes. A bill pending in the D.C. Council would undermine that expectation and subject residents to unwarranted risks from convicted murderers, rapists and child sex abusers.

The legislation would directly benefit the most serious and violent criminals — specifically, those who killed, raped or committed sexual abuse before reaching age 25 — by making them eligible for release, or a reduced sentence, while still in their 30s.

It’s important to be clear about the implication of the pending legislation, sponsored by D.C. Council member Charles Allen (D-Ward 6): Under the bill, if the gunmen who massacred innocent people in El Paso and Dayton, Ohio, this month had instead committed their crimes in the District — and had both survived — one would be eligible for release or reduced sentence at age 36, at a judge’s discretion; the other at age 39.

In addition, a measure enacted earlier this year by the council and signed by Mayor Muriel E. Bowser (D) eliminated a requirement that judges consider the circumstances of the crime when an offender asks for a shorter sentence. So if a judge focused on the brutality of a murder in denying a petition, he or she might receive a personal reprimand from Mr. Allen — who did just that earlier this summer, in the case of a convicted child rapist whose request for a reduced sentence was denied by a Superior Court judge.

That’s insupportable, and in fact, it’s highly doubtful that most citizens of the District would support such a measure.

A recently enacted bill allows convicts who offended at age 16 or 17 to file such sentence-reduction requests after serving just 15 years behind bars, down from 20 years, even if they are not yet eligible for parole. Pending legislation would expand the potential beneficiaries to include offenders who committed violent crimes up to age 25. If it passes, they would be eligible for a reduced sentence before they hit age 40. And Mr. Allen’s intent is that they be assessed mainly on their conduct in prison and — this is squishier — the extent of their sincere rehabilitation.

The bill’s advocates, including D.C. Attorney General Karl A. Racine, cite neuroscience in contending that youthful offenders — impetuous, peer-pressured and oblivious to consequences — cannot fairly be held accountable for their crimes years later when they are mature. But the ostensible scientific evidence is window dressing for the proponents’ real goal, which is more generally to limit incarceration even for the most serious crimes.

It’s fair to debate sentencing reform: Several Scandinavian countries, among others, have relatively short prison terms for murderers and other violent felons. But the District’s politicians should be clear about their agenda. If they want to slash sentences for violent offenders — many or most of whom are in their 20s — let them make that case clearly and honestly. But by having judges hand down decades-long sentences, and then allowing even the most brutal convicts to seek release before they reach age 40, lawmakers are doing something different. They’re deceiving the public and fooling victims.

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