This paper, prepared for the University of Frankfurt Symposium on Defeasibility in Epistemology, Ethics, law and Logic, addresses the claim of H.L.A. Hart and others that law is open-textured. It is in the nature of law, they say, that it necessarily possesses an open texture going beyond the open texture of the language in which legal rules are written. But when we examine the question of open texture in light of Hart’s claim that the open texture of law entails the necessary defeasibility of legal rules, we discover that Hart and his followers are mistaken. Both the alleged open texture of law qua law (as opposed to the open texture occasioned by the open texture of the language used by law) and the defeasibility of legal rules are contingent features of certain legal rules in certain legal regimes, but neither are necessary components of the nature of law or the nature of rules.