In his provocative new book, A Realistic Theory of Law, Brian Tamanaha offers a variety of insightful analyses and conclusions that may shake up analytical jurisprudence for years to come. In the course of a relatively short and highly accessible work, Tamanaha challenges conceptual theories of law and conventional understandings of international law, clarifies important aspects of legal pluralism, and provides a novel, genealogical approach to thinking about the nature of law. It would take a whole other book (and likely a much longer one) to give due consideration to all of these topics, so the focus of this commentary must necessarily be much narrower. In this article, I focus on Tamanaha’s argument for a greater appreciation of historic...