Obama commutes sentences of 42 prisoners

US President Barack Obama will "reaffirm the American commitment to Poland's security" during his forthcoming visit to Europe (AFP Photo/Jim Watson) (AFP)

Washington (AFP) - US President Barack Obama on Friday commuted the prison sentences of 42 people, most of them non-violent drug offenders, reflecting his calls for criminal justice reform.

Most of those pardoned were small-time drug dealers who received long sentences under a code shaped by the government's war on drugs.

The punishments were made under "outdated and unduly harsh sentencing laws," the White House said in a statement.

"The individuals receiving a presidential commutation today have more than repaid their debt to society and earned this second chance."

Some were serving life sentences. Held in various prisons across the country, they will be released between October 1, 2016 and June 3, 2018.

Obama has now commuted sentences for 348 people, more than the total amount issued by the previous seven presidents combined.

Obama has called for legislation to reduce sentences and provide alternative punishments for small-time offenders.

"There remain thousands of men and women in federal prison serving sentences longer than necessary, often due to overly harsh mandatory minimum sentences," the White House said.

Some 2.2 million people are behind bars in the United States, a quarter of the world's prisoners in a country with only five percent of the world's population.

They include legions of the mentally ill and drug addicts, often from disadvantaged minorities, in a prison system many experts criticize for encouraging high rates of recidivism.