Written as a comment on Philip Hamburger's book, Law and Judicial Duty, this essay explains why the history of judicial review remains a difficult area for scholarship. American judicial tradition espoused that judges had an obligation to declare as void laws repugnant to the constitution. The essay suggests that the source of this duty, as well as the meaning of both the constitution and laws of the land, changed over time. The essay proposes that scholars perceived American judicial review as problematic only when this tradition conflicted with an increasingly rigid belief in separation of powers. The essay concludes by suggesting that Marbury's significance derives from its status as the last time an American judge could declare that striking down a law as repugnant to a constitution was the simple consequence of expounding the law. The comment ultimately argues for recovering the time-honored meaning of "expounding" as applied to the work of judges.