"The racial disparities in the rates of drug arrests culminate in dramatic racial disproportions among incarcerated drug offenders. At least two-thirds of drug arrests result in a criminal conviction.18 Many convicted drug offenders are sentenced to incarceration: an estimated 67 percent of convicted felony drug defendants are sentenced to jail or prison.19 The likelihood of incarceration increases if the defendant has a prior conviction.20 Since blacks are more likely to be arrested than whites on drug charges, they are more likely to acquire the convictions that ultimately lead to higher rates of incarceration. Although the data in this backgrounder indicate that blacks represent about one-third of drug arrests, they constitute 46 percent of persons convicted of drug felonies in state courts.21 Among black defendants convicted of drug offenses, 71 percent received sentences to incarceration in contrast to 63 percent of convicted white drug offenders.22 Human Rights Watch’s analysis of prison admission data for 2003 revealed that relative to population, blacks are 10.1 times more likely than whites to be sent to prison for drug offenses.23"

Source

Fellner, Jamie, "Decades of Disparity: Drug Arrests and Race in the United States," Human Rights Watch (New York, NY: March 2009), p. 16.
http://www.hrw.org/sites/defa…