Law as a Function of Time
Can a law change over time? This has been the central question of legal scholarship over the past century. On the one hand, advocates of living constitutionalism argue that judges should adapt laws to changed circumstances. On the other hand, originalists argue that laws should be interpreted as they were understood at the time they were enacted. Yet even within an originalist framework, judges should—and indeed must—interpret laws differently at different times, if that is what the law was originally understood to do when enacted.
This jarring conclusion is apparent in the provisions of the Constitution itself. For example, the Constitution permitted the continued importation of slaves until 1808 but not thereafter. This sunset clause explicitly requires different outcomes at different times (before vs. after 1808). The Constitution also permits the writ of habeas corpus to be suspended when required by public safety in cases of rebellion or invasion. The Suspension Clause thus implicitly incorporates a time-dependent variable: whether or not there is a rebellion or invasion.
Building on this insight, this Article proposes a mathematical framework to analyze how laws can legitimately vary over time, even within the framework of originalism. It leverages tools from mathematics to show how some laws explicitly vary over time (e.g., sunset clauses) and how other laws implicitly vary over time by incorporating by reference laws, facts, customs, or theories that may in turn vary over time. The Article then imports concepts from set theory to illustrate other mechanisms of changed applications: interpreting laws in light of new objects, doctrinal developments, and stare decisis.
Cite as Michael K. Velchik, Law as a Function of Time, 18 N.Y.U. J.L. & Liberty 400 (2025).