Theory: Precedent might affect Supreme Court decision making in a number of ways. One conception, the conventional view scrutinized by Segal and Spaeth, sees precedent as the primary reason why justices make the decisions that they do. A second regards precedent as a normative constraint on justices acting on their personal preferences. On this account, justices have a preferred rule that they would like to establish in the case before them, but they strategically modify their position to take account of a norm favoring respect for precedent in order to produce a decision as close as is possible to their preferred outcome. Hypothesis: If precedent is a norm, researchers would be unlikely to detect its presence by conventional examinations of the vote. Rather, it would manifest itself throughout the decision making process in some of the following ways: attorneys' attention to precedent and justices' appeals to and respect for the doctrine. Methods: Counts of attorneys' use of authorities in written briefs, of justices' appeals to precedent during conference discussion, of justices' invocation of precedent in their opinions, anid of the Court's alterations of stare decisis. Results: Since the data support our account of stare decisis as a norm that structures judicial decisions, we question research designs that focus solely on how precedent affects the disposition of cases.