The usual “tests” for vagueness—fair notice to ordinary citizens from the language of the statute and fear of arbitrary enforcement—provide superficial explanations for applications of the vagueness doctrine. We believe that the Robinson conduct requirement and the Bouie–Shuttlesworth correlation requirement have significantly greater explanatory power in supporting a conclusion that a statute is or is not unconstitutionally vague. Attention to these principles can provide meaningful insight into whether a statute has transgressed acceptable vagueness limits. They are not, of course, mechanical or coldly analytical. Judgment is still required, in part to take into account countervailing factors such as the necessity of the chosen means to accomplishment of the legislative objective and the legitimacy and seriousness of that objective. And additional considerations beyond the four corners of the vagueness doctrine, however it is explained, will often be determinative of the outcome. In any event, we submit, explicit consideration of the two principles we have advanced will give much more fulsome content to the vagueness doctrine than is revealed by the traditional manner in which it is described. Thinking about vagueness in this manner may not change outcomes or make hard cases any easier, but it will assist deliberation and will provide a more convincing rationale once a conclusion is reached.
The vagueness doctrine serves important rhetorical purposes. It is embedded in more than a century of litigation that for the most part has led to defensible results. Our claim is that analytical clarity can be achieved and that more meaningful exposition will occur if the traditional analysis is employed with the conduct requirement of Robinson and the correlation requirement of Bouie more transparently in mind. The rest we would leave as it is.