In this Article ProfessorMeyer examines legal indeterminacy in the contexts of Rule 11 and qualified immunity doctrine, two are as in which the law acknowledges its own indeterminacy. Drawing from both legal theory and legal practice, she finds that legal indeterminacy serves important purposes as a kind of legal practice, rather than as a description of legal practice. Indeterminacy preserves the legitimacy of the law, Professor Meyer concludes, because law is a practice in time. In the Rule 11 context, she argues, legal indeterminacy protects lawyers who make losing arguments about real harms and important values in order to preserve those arguments for possible future law. In the qualified immunity context recognizing legal indeterminacy protects government officials who, because of gaps or ambiguities in the law, have not had fair notice that their past actions violate the law. The different temporal focuses explain why indeterminacy looks somewhat different in the two contexts. Because Rule 11 protects the future of the law–the possibilities that have not yet been clarified–the doctrine tends to take a “radical” approach to indeterminacy. Since qualified immunity doctrine is concerned with the past aspect of law, it tends to be more positivist: law is what judges have said it is, and law Is indeterminate where there are “legal gaps” and no court has articulated a rule. In some cases, Professor Meyer contends, such a positivist approach causes courts to lose sight of the fact that some law is not written because it has never needed to be but is taken for granted as an element of obvious, universal human norms.