The Attorney General moved to end the disparity in sentencing for people convicted of crimes related to crack and power cocaine.
Garland told prosecutors that the disparity is not supported by science and that there are no significant differences between the drugs.
There is a mandatory prison sentence of five years for offenses involving 28 grams of crack cocaine and 500 grams of powder cocaine.
According to the US Sentencing Commission, Black people are convicted of crack offenses at a higher rate than White people.
Most of the people who were convicted of selling crack cocaine were black, while 15 percent were Hispanic and 6 percent were white in 2011.
Almost 67 percent of individuals convicted of cocaine dealing were Hispanic; 25 percent were black and 7 percent were white.
Minimum sentences for crack convictions will be changed in 30 days when the revised policy takes effect.
The memo instructs prosecutors to consider whether or not violence was involved in the crime, as well as whether or not individuals had a significant managerial role in the trafficking of significant quantities of drugs.
The impact that sentencing guidelines have on Black Americans has been pointed out by civil-rights groups for a long time.
The purpose of the sentencing disparity is to put black Americans in jail. The NAACP president said in a statement that it was all done. There is no scientific reason for sentencing crack and powder offenses in a different way. The failed War on Drugs has been used to lock our community up in jail.
Garland's announcement is a step towards restoring faith in the criminal justice system.
The Equal Act would end the crack-to-powder disparity on the federal level.