Do Theories of Statutory Interpretation Matter? A Case Study

Statutory interpretation has been a fertile area of scholarship, but we know relatively little about the practical impact of various theories of interpretation. The ideal test would involve presenting randomly selected cases to two judges who are similar in most other respects but have sharply different theories of interpretation. As it happens, such a situation is presented by Judges Posner and Easterbrook, who have sat together on over 800 reported panel decisions. (Because en banc cases are subject to selection bias, they are discussed separately in the paper.) Posner is a leading advocate of pragmatism, while Easterbrook is equally well-known for his support of formalism. As it turns out, the two judges voted differently in only one percent of these roughly 800 cases. This is substantially below the average level of disagreement among Seventh Circuit judges, and is also below the average rate for courts of appeals generally. Moreover, a careful examination of the statutory cases in which the two judges disagreed confirms that their theoretical disputes were not outcome determinative. Because Posner and Easterbrook have shown particularly serious interests in theories of interpretation (compared to most judges), the apparently slight level of impact on outcomes seems especially surprising. While far from definitive, this study suggests strongly that the conventional wisdom on this point significantly overestimates the impact of a judge's theoretical stances on voting behavior.