JUSTICE SYSTEM JOURNAL, 00(0), 1–16, 2015 Copyright C  Taylor & Francis Group, LLC ISSN: 0098-261X print / 2327-7556 online DOI: 10.1080/0098261X.2015.1024569 Statutory Language and the Separation of Powers Rebecca Reid Department of Political Science, Universityof Texas, El Paso, El Paso, Texas Kirk A. Randazzo Department of Political Science, University of South Carolina, Columbia, South Carolina 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. KEYWORDS: vagueness doctrine, statutory language, Supreme Court, separation of powers The ability of the U.S. Supreme Court to declare congressional statutes unconstitutional repre- sents one of the Court’s greatest powers. Because the Constitution provides Congress the authority to make law and provides the judiciary the authority to interpret the law, this joint legal authority often creates tension and an “invitation to struggle” between the legislative and judicial branches in determining the law (Corwin 1957, 171). Scholars examining these struggles often rely on separation of powers (SOP) models to determine whether one particular branch of government (typically the judiciary) defers to the ideological preferences of another branch (often the legisla- ture) 1 in order to avoid having a particular decision overturned at a later stage—thereby resulting in a worse policy outcome. Yet, despite the theoretical and methodological advancements of these SOP models, they continue to overlook the legal aspect of law development by focusing solely on the policy preferences of each institution (but see Randazzo, Waterman, and Fine 2006; Randazzo and Waterman 2011). We argue that overlooking statutory language and detail compromises our understanding and evaluation of the separation of powers because the language of the law included Address correspondence to Rebecca Reid, 500 W. University, Benedict Hall 111, Department of Political Science, University of Texas, El Paso, El Paso, TX, 79968. E-mail: reidrebecca66@gmail.com Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ujsj. 1 Separation of powers models may also include the ideological distance between the Court and the president in addition to between the Court and Congress. In order to avoid repetition, and since we are primarily interested in the relationship between the Supreme Court and Congress, we assume throughout the article that similar arguments can be made in reference to the president as are made to the legislature.