The fact that a substantial percentage of Supreme Court decisions are unanimous is often used to undermine the theory that the Court’s decisions are ideologically driven. We argue that if the ideological stakes in a case are small, even slight dissent aversion is likely to produce a unanimous decision. The data support this interpretation but also establish the existence of an ideological effect in unanimous decisions. These findings are consistent with a realistic conception of the Court as a mixed ideological–legalistic judicial institution.
