Vertical Precedents in Formal Models of Precedential Constraint

Abstract

The standard model of precedential constraint holds that a court is equally free to modify a precedent of its own and a precedent of a superior court — overruling aside, it does not differentiate horizontal and vertical precedents. This paper shows that no model can capture the U.S. doctrine of precedent without making that distinction. A precise model is then developed that does just that. This requires situating precedent cases in a formal representation of a hierarchical legal structure, and adjusting the constraint that a precedent imposes based on the relationship of the precedent court and the instant court. The paper closes with suggestions for further improvements of the model.

Keywords: Legal reasoning, Factor-based reasoning, Precedent, Common law, Default reasoning