This work investigates the historical evolution and legal conceptualization of custom as a source of law within the Western legal tradition. Francesca Iurlaro, a scholar of legal history, examines how medieval and early modern jurists transformed social practices into binding legal norms. The book analyzes the tension between written statutes and unwritten customary practices, providing a framework for understanding how legal authority is constructed over time.

Experts in legal history recognize this text as a rigorous examination of the intellectual foundations of customary law. Readers frequently note the academic density of the prose, which is intended for scholars and students of jurisprudence.