(source: U.S. Centers for Disease Control)
The mere fact that blacks are overrepresented in American prisons relative to the population does not even come close to proving the American justice system is racist, because:
One of the most well-known statistics pertaining to the criminal justice system is that a disproportionate amount of African American males are arrested, convicted, and incarcerated. Although the precise estimates vary across studies and reports, in general African American males are arrested at a rate (relative to their proportion of the population) several times that of White males, with these racial differences being quite robust across a wide range of offenses, including property offenses and drug-related offenses (Cooper, Fox, & Rodriguez, 2012; Peterson, 2012; Sampson & Wilson, 2005; Steffensmeier, Feldmeyer, Harris, & Ulmer, 2011; Tonry, 2010). This disparity is even more pronounced when examining the most serious and violent types of criminal acts (Chan, Myers, & Heide, 2010; D’Alessio & Stolzenberg, 2003; DeLisi, Dooley, & Beaver, 2007; Gabbidon, Higgins, & Potter, 2011; Tapia, 2010; Tillyer & Hartley, 2010; Tonry, 2010). In short, no matter how the data are cut, no serious criminologist, sociologist or any other academician interested in the topic can deny that African American males are much more likely to be processed through the criminal justice system than are White males.
Where opinions differ sharply, however, is in regard to the exact mechanisms that predict disparities in criminal justice processing. While several causal pathways have been proposed, the explanation garnering the most attention from scholars is that of a racially biased justice system (Kennedy, 1997; MacDonald, 2003; Wilbanks, 1987). More specifically, the null hypothesis, so to speak, has been that of a system which unduly targets racial minorities, especially African Americans. Certainly there is evidence pertaining to the increased likelihood of African American males (in particular) being stopped, questioned, arrested and ultimately sentenced by the criminal justice system (Blumstein, 1982; Carmichael, 2010; Kennedy, 1997; Peterson, 2012; Tonry, 2010; for some dissenting evidence, however, see Franklin, 2010, as well as, Tracy, 2002).
This is the introduction to an article with the self-explanatory title: No evidence of racial discrimination in criminal justice processing: Results from the National Longitudinal Study of Adolescent Health, published in the peer-reviewed journal Personality and Individual Differences. Many commentators seek to explain higher crime rates among American blacks as a product of discriminatory enforcement, so the authors decided to look at self-reports of behavior given as part of a huge anonymous US federal study. They found that self-reporting closely tracked official crime statistics. The authors of course note that self-reporting has limitations, but they observed that (1) since the study was anonymous, participants were unlikely to be distorting their answers to influence peers, and (2) in any case, people asked to report on their own antisocial behavior consistently understate it, for reasons that should be obvious to everyone.
Nevertheless, the amount of criminal activity reported by blacks was largely in line with statistical evidence of higher proportions of blacks being processed through the justice system. I wouldn't go so far as to absolve the US criminal justice system of all discrimination, but merely citing the over-representation of one group in US prisons without this vital context is misleading and German journalists should stop doing it. Nor, for that matter, should American journalists conclude from the fact that 27% of all German prisoners are foreigners (g) that the German criminal justice system is biased.