We develop an informational model of judicial decision-making in which deference to precedent is useful to policy-oriented appellate judges because it improves the accuracy with which they can communicate legal rules to trial judges. Our simple model yields new implications and hypotheses regarding conditions under which judges will maintain or break with precedent, the constraining effect that precedent has on judicial decision-making, the voting behavior of Supreme Court Justices, the relationship between a precedent's age and its authority, the effect of legal complexity on the level of deference to precedent, the relative stability of rules and standards, and long-term patterns of legal evolution. Perhaps most importantly, we demonstrate that “legalist” features of judicial decision-making are consistent with an assumption of policy-oriented judges.