WASHINGTON: A push to overhaul criminal sentencing is prompting the early release of thousands of federal drug prisoners, including some whom prosecutors once described as threats to society, according to an Associated Press review of court records.

About 6,000 inmates are due to be freed from custody in the coming month, the result of changes made last year to guidelines that provide judges with recommended sentences for specific crimes. Federal officials say roughly 40,000 inmates could be eligible for reduced sentences in coming years.

Many of them are small-time drug dealers targeted by an approach to drug enforcement now condemned by many as overly harsh and expensive. But an AP analysis of nearly 100 court cases also identified defendants who carried semi-automatic weapons, had past convictions for robbery and other crimes, moved cocaine shipments across states, and participated in international heroin smuggling.

Supporters of lighter drug sentences say there's no evidence that longer punishment protects public safety. Studies show that inmates released early aren't more likely to re-offend than those who serve their entire sentences.

Still, the broad spectrum of defendants granted early release — including some about whom prosecutors not long ago raised dire warnings — underscores the complex decisions confronting the government as it pursues an overhaul of drug sentencing.

"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 I think that we need to be smart about deciding who are those dangerous people."

Willie Best, a one-time District of Columbia drug dealer whose sentence was already slashed under past crack guideline changes, had an additional month taken off and is due out in 2016.

Prosecutors in 2008 said Best helped run a drug-dealing organisation, shot at someone he believed had stolen from him and, after fleeing as warrants were served, was found in a stolen car with an assault rifle and other guns. His lawyer described him as the product of a troubled, impoverished upbringing. And Best, in an interview from prison, called himself a loving father who bears no resemblance to his past self.

"It's been a long time coming. Eight years is a long time," he said. "I came in one way. I'm coming out another."

Guidelines set by the US Sentencing Commission offer 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 to be public safety threats. About three-quarters of requests had been granted as of August.

The first wave is due around November 1, and most of those getting early release are already in halfway houses or under home confinement. Others will be released to immigration authorities for eventual deportation.

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

The commission delayed implementation by a year to allow judges time to review requests and weed out inappropriate candidates and to arrange for defendants to be moved to halfway houses.

"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, along with an Obama administration clemency initiative and directives against mandatory minimum sentences, is part of a national effort to rethink punishments for a drug offender population that comprises roughly half the federal inmate count.

New bipartisan legislation in the Senate 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. House lawmakers are also expected to unveil criminal justice legislation this week.

Supporters call the commission's move, which would on average pare two years from sentences and in many cases just months, a modest dialing-back of punishments that were too harsh to begin with and wouldn't be imposed today.

Research shows "longer lengths of stay cost taxpayers a tremendous amount but don't add any additional crime-control value," said Adam Gelb, a Pew Charitable Trusts criminal justice expert.

But absent foolproof formulas, judges are grappling with balancing cost against public safety.

The issue arose last month in Washington, D.C., where a judge rejected early release bids from two organizers of a 1980s-era cocaine trafficking operation. Though both were sentenced in 1990, the judge declared them to be continuing threats and chastised prosecutors for appearing to dismiss the pair's involvement in violent and calculating crime.

Others with shortened sentences are defendants whom prosecutors said had squandered repeated opportunities.

Regis Payne is due out in 2017 after his 82-month sentence for selling PCP in the District of Columbia was cut to 60 months. Before his 2012 sentencing, prosecutors called him a "calamity waiting to happen," undeterred by past convictions. Roscoe Minns was cleared for release in November, though prosecutors in 2012 highlighted prior assault and theft convictions in pursuing stiff punishment.

Though some released early will reoffend, most will not, statistically speaking, said Ohio State law professor Doug Berman.

"Mark my words: The sky will not fall," said Julie Stewart of Families Against Mandatory Minimums.

Tuan Evans, who sold pistols and cocaine to undercover officers, had 11 months shaved off his 108-month sentence. He wrote from prison that he's acquired haircutting skills and hopes to start a landscaping business and mentor children once he's freed. Records show a 2018 release date.

"You don't have to lock us up and throw away the key when we make a mistake," he said.