The connection between social identity and attitudes toward the criminal justice system (CJS) is an area of interest among criminologists and legitimacy scholars. Previous work has proposed a social identity theory of legitimation, positing that individuals categorize CJS officials as either in-group (i.e. legitimate authority) or out-group (i.e. illegitimate enforcer). Subsequently, how individuals perceive their CJS – including the sincerity of its commitment to the rule of law – is tied to this relationship. Those viewing the government as an out-group oppressor are less likely to accept its legitimacy. This article explores this thesis. From the perspective of system justification theory, how the CJS is categorized should depend on how strongly an individual identifies as belonging to a group disadvantaged by the CJS. System justification theorists hypothesize that system justification (including acceptance of system legitimacy) is more likely when members of disadvantaged groups believe that group interests are less important. Alternative models that explain attitudes toward the system by using social identity theory suggest the opposite: Those who identify more strongly with disadvantaged groups and hold their interests to be more important nonetheless justify oppositional systems and view them legitimately. The present study uses a sample of Black Americans (a disadvantaged group in the American CJS) to determine whether group identification predicts system justification.