The canon of constitutional avoidance is jurisprudentially important but poorly constructed. The Supreme Court frequently uses the canon in significant cases to justify second-best interpretations of statutes that avoid serious constitutional questions. Nevertheless, the trigger for the application of the avoidance canon, textual “ambiguity,” has not been coherently developed by the Court and differs in important ways from ambiguity as linguists typically view it. In addition, the Court, in focusing on “ambiguity” as a precondition for the application of the avoidance canon, fails to recognize the different ways in which a statute might be indeterminate. Recently, the Court reaffirmed its conception of the avoidance canon in a case, Jennings v. Rodriguez, involving prolonged immigration detention. In Rodriguez, the Court focused on ambiguity to the exclusion of other types of linguistic indeterminacy and continued to defend an unduly narrow conception of ambiguity that rejects implicit limitations on the scopes of statutes. This Article argues that the Rodriguez case highlights the need for the Court to reassess the avoidance canon. By doing so, the Court can give the avoidance canon a more defensible foundation that is consistent with the ways in which language operates.