The most enduring question in the study of judicial behavior is the relative importance of legal and policy considerations in shaping the Supreme Court’s decisions on the merits and the positions of individual justices in those cases. This chapter analyzes what we have learned about that question. On the theoretical side, the framework of motivated reasoning shows why we would expect policy considerations to play a central part in decision making, and it also shows why legal considerations are likely to have substantial impact on the justices’ choices. The empirical research on law and policy in the Court’s decisions has informed our understanding of decision making in important ways, but the evidence it has produced is far from definitive. The lack of definitive findings largely reflects the difficulty of measuring key variables, including the justices’ policy preferences and the state of the law as it applies to particular cases. Further progress in identifying the roles of law and policy in decision making will be enhanced by further improvements in measurement. It would also be a good step to give more attention to justices’ cognitions alongside their motivations.