This Essay provides an originalist appraisal of Professor James Bradley Thayer’s famous book on The Origin and Scope of the American Doctrine of Constitutional Law. I critique Professor Thayer’s thesis on multiple levels, pointing out important aspects of the original understanding that the Framers would have had of the meaning and origins of the U.S. Constitution, as well as disputing Professor Thayer’s discussion of the history of American judicial review from 1790 to the publication of his book in 1893. I conclude that no person can be both an originalist and a Thayerian. The two theories contradict one another and cannot be jointly adhered to. I then explain why I prefer originalism to Thayerianism as a normative matter.