Social Identity Group Cues in Judicial Ideology and Decision-Making on the U.S. Supreme Court

While interest group influences on U.S. Supreme Court decisions have been extensively studied, research on the role that litigants’ social identity group cues play in judicial ideology and decision-making is in its infancy. We hypothesize that justices will rely on both their policy preferences and group cues to decide cases. To test these hypotheses, we develop new measures of litigant social group identity, relying on both left-right ideology and political culture. We employ these measures using ideologies and political cultures advanced in one set of cases to predict those advanced in another set of cases between 1946 and 2001. As expected, we find that ideology, political cultural values, and litigant social group identities have both independent and interactive effects on judicial decisions, with group identities having a bigger impact among moderate justices.