In an emotional open letter published Friday in Rolling Stone, singer John Legend asked President Barack Obama to grant clemency to non-violent drug offenders before leaving office in 2017.

AP/Chris Pizzello - apimages.com

Legend wrote that he has appreciated some of the president's decisions regarding incarceration, such as his ban of solitary confinement for juvenile offenders in federal prisons earlier this year. The artist would like to see Obama take his efforts further by "granting as many clemencies as possible before [leaving] office." Legend called "the War on Drugs and America’s addiction to incarceration" a moral failure. 

During his presidency, Obama has commuted the sentences of 1,023 males and females who were "incarcerated under outdated and unduly harsh sentencing laws," the White House states on its website. The majority of these individuals were non-violent drug offenders.

"I urge you to consider issuing categorical commutations to bring an end to the injustice that remains in our federal sentencing schemes," Legend wrote. "For example, approximately 5,000 individuals are serving sentences based on prejudiced laws which punished drug crimes involving crack cocaine more severely than crimes involving powder cocaine. Rectifying these crack-powder disparities would not only correct the mistakes of the past, but could save taxpayers just over $150 million per year and keep with public sentiment about the over-incarceration and criminalization of drug crimes."

This issue is personal for Legend, whose mother struggled with drug abuse and spent time in jail. He wrote in a July 2015 piece for TIME that his mother "didn’t need punishment" for her drug addiction, "she needed help." Several months prior to writing that piece, Legend announced the start of his organization Free America, a campaign for prison reform.

"We have a serious problem with incarceration in this country," Legend told the Associated Press in April 2015. "It's destroying families, it's destroying communities and we're the most incarcerated country in the world, and when you look deeper and look at the reasons we got to this place, we as a society made some choices politically and legislatively, culturally to deal with poverty, deal with mental illness in a certain way and that way usually involves using incarceration."

U.S. Department of Justice - wikimedia.org

According to the Prison Policy Initiative, one in five people are imprisoned for a drug offense, and non-violent drug offenses "are a defining characteristic of the federal prison system."

"Unlike in the states, drug offenses are a major driver of the federal prison system," the Urban Institute, an educational nonprofit, states on its site. "Substantial reductions to the [Bureau of Prisons] population can be achieved by reforming sentencing law and policy for drug trafficking."

However, reducing the prison population will take more than just focusing on non-violent offenders. Robert Weisberg, a Stanford University professor of law, told ATTN:'s Danielle DeCourcey in May that the U.S. justice system should consider freeing violent offenders who are no longer considered a risk for the system to be more effective. He added that violent offenders who committed crimes in their 20s or 30s tend to "age out of their crime" when they are older.

"The most interesting example of people who should be considered for release and unquestionably committed violent crimes, but are not dangerous anymore, are elderly people," Weisberg said.

Read Legend's full letter here.