"... blacks are just 12 percent of the population and 13 percent of the drug users, and despite the fact that traffic stops and similar enforcement yield equal arrest rates for minorities and whites alike, blacks are 38 percent of those arrested for drug offenses and 59 percent of those convicted of drug offenses. Moreover, more frequent stops, and therefore arrests, of minorities will also result in longer average prison terms for minorities because patterns of disproportionate arrests generate more extensive criminal histories for minorities, which in turn influence sentencing outcomes."

Source

Welch, Ronald H., and Angulo, Carlos T., Leadership Conference on Civil Rights, "Justice on Trial: Racial Disparities in the American Criminal Justice System" (Washington, DC: Leadership Conference on Civil Rights, May 2000), p. 7.
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