Traditional separation of powers models assert that the Supreme Court takes into consideration the policy preferences of other institutions and behaves strategically so as to place legal policy at its preferred policy point. The vagueness doctrine, however, asserts that the Court determines statute constitutionality not from strategically calculating institutional ideological preferences but from the degree of specificity of the statute's language itself. This study finds that the vagueness doctrine better predicts Court declarations of unconstitutionality than preference-based models, suggesting that the language of the law itself is crucial to statutory decisions.