Abstract: Chief Justice Roberts's metaphor of judges as umpires has been often criticized for being a bad theory of legal adjudication. Critics of Roberts's metaphor argue that judges are not mechanical reporters of clear-cut normative truths, but little attention has been paid to the question whether calling balls and strikes is indeed mechanical. The traditional theory, shared by both Roberts and his critics, is that "truth in baseball is clear-cut." In this Article, I argue that this theory of baseball is mistaken. Calling balls and strikes, despite its apparent simplicity, is an inherently interpretive practice. It is shaped not only by clear-cut rules, but also by shared practices and unwritten principles on how the game ought to be played.