When courts decide cases, the decisions make law because they become precedent that binds future courts under the doctrine of stare decisis. This article argues that some principles governing judicial lawmaking are functionally constitutional principles because they go to the validity of a particular attempt at judicial lawmaking (just as the constitutional principles governing legislative lawmaking determine the validity of lawmaking by legislatures). Because even poorly reasoned judicial decisions can still be effective lawmaking acts, it is important to distinguish between constitutional and non-constitutional principles and arguments. While a non-constitutional principle can be a basis for examining the wisdom or merits of a particular lawmaking act, only constitutional principles can assess whether the lawmaking act is valid.

Although the constitutional principles governing judicial lawmaking are not necessarily set forth in a written constitution, this article articulates a methodology for identifying the fundamental constitutional limits on judicial lawmaking. It then explains how this constitutionalist approach fits with various strands of legal theory, including formalism, realism, positivism, legal process, and critical legal studies. Finally, this article begins to examine the implicit constitution that governs judicial lawmaking in the federal system, explicating some of the key issues that define its contours and that can shape future development and critique.