WASHINGTON — Drug criminals once described by prosecutors as unrepentant repeat offenders are among those poised to benefit from new sentencing guidelines that are shrinking punishments for thousands of federal prisoners, according to an Associated Press review.

Many defendants cleared for early release starting this fall fit a more sympathetic profile: small-time dealers targeted by a draconian approach to drug enforcement.

But an AP analysis of roughly 100 court cases also identified defendants who carried semi-automatic weapons, had past convictions for crimes including robbery and assault, moved cocaine shipments across states and participated in international heroin smuggling.

One inmate whose punishment was cut was described in 2012 as a “calamity waiting to happen.” Another was caught with crack and guns while awaiting sentencing in a separate drug case.

Supporters of lighter drug sentences say there’s no evidence that lengthier sentences protect public safety, and there’s bipartisan determination to cut spending on a bloated federal prison system.

Nonetheless, the broad spectrum of defendants granted early release, including some who prosecutors just a few years ago branded community dangers and were the subject of dire warnings, underscores the complex decisions confronting the government as it updates a drug sentencing structure many see as overly harsh and expensive.

“I’m a career prosecutor. I’m a law-and-order girl, and I believe that you need to send dangerous people to prison for a very long time,” said Deputy Attorney General Sally Yates.

“But,” she added, “I think that we need to be smart about deciding who are those dangerous people.”

Guidelines set by the U.S. Sentencing Commission provide judges recommended minimum and maximum terms for federal crimes. The independent commission voted last year to reduce ranges for drug offenses, then applied those changes to already-imprisoned convicts.

Since then, prisoners have sought relief from judges, who can reject those they consider public safety concerns. About three-quarters of requests had been granted.

The first wave, some 6,000, is due around Nov. 1, with most released from halfway houses or home confinement. Others will be released to immigration authorities for deportation. Federal officials say roughly 40,000 prisoners will be eligible for reductions.

Though the commission has repeatedly amended the guidelines, including narrowing the disparity between crack and powder cocaine sentences that resulted in disproportionately long penalties for blacks, the latest revision is its most sweeping because it covers all drug types.

“Nothing to date comes close to what this shift is likely to produce over the next decade or so, starting this year,” said Marc Mauer of the Sentencing Project, an advocacy group.

The action is part of a national effort to rethink punishments for a drug offender population that comprises roughly half the federal inmate count.

In addition to an Obama administration clemency initiative and directives against mandatory minimum sentences, new bipartisan legislation aimed at reducing spending on a prison system that sucks up nearly one-third of the Justice Department budget would give judges greater sentencing discretion and ease penalties for nonviolent criminals.