President Barack Obama speaks in the East Room of the White House in Washington, July 13, 2015.
President Barack Obama speaks in the East Room of the White House in Washington, July 13, 2015.

U.S. President Barack Obama has cut the prison sentences of 46 non-violent offenders, as part of a push to reform the nation's chronically overcrowded federal prison system.

In a White House video released Tuesday, Obama said "these men and women were not hardened criminals, but the overwhelming majority had been sentenced to at least 20 years."

The president has now issued nearly 90 commutations during his presidency, with most of them targeting offenders imprisoned for drug crimes who met new criteria established by the Justice Department last year.

The commutations leave the convictions in place, while ending the punishment.

White House counsel Neil Eggleston said he expects the president to issue more commutations and pardons before he leaves the White House in 2017.

The White House says Obama will elaborate on plans to improve the fairness of the criminal justice system in an address to the the National Association for the Advancement of Colored People (NAACP) on Tuesday.

Administration officials have described reform efforts as a push to give relief to inmates jailed under harsh mandatory sentencing guidelines formulated in the 1980s, at the height of the crack cocaine epidemic.

The commutations include the case of Stephen Donovan, a Wisconsin native who along with three accomplices was charged in 1992 with conspiracy to deliver dozens of kilograms of cocaine purchased elsewhere.  

The Milwaukee Journal-Sentinel, quoting court records, said Donovan -- unlike his accomplices -- had two prior marijuana convictions.  He therefore faced mandatory life imprisonment without the possibility of parole under controversial "three strikes" penalties widely imposed by courts in that era.  

At his sentencing, his lawyers unsuccessfully argued that it was unconstitutional to impose a life sentence for a non-violent crime. He was 35-years-old at the time.

Donovan's current lawyer is quoted as saying his now 58-year-old client will likely be transferred from a federal prison to a halfway house before his release.

The presidential decree orders all 46 inmates released by November 10.