Chevron as a Canon, Not a Precedent: An Empirical Study of What Motivates Justices in Agency Deference Cases

Abstract

Legal scholars and jurists believe that federal judges often defer to agency interpretations of statutes. Debate has focused on when judges should defer and how judges should operationalize a deference regime doctrinally, perhaps as a matter of stare decisis. Such normative debates about deference rest upon assumptions that have not been rigorously tested, however. Examining the entire population of Supreme Court cases where an agency interpretation was in play (1984-2006), our empirical study finds that the Justices do not generally give deference-regime precedents anything close to stare decisis effect, but that the policies underlying the major deference regimes do have a discernible effect at the Supreme Court level. We also find that judicial ideology affects the justices' applications of deference regimes. As a descriptive matter, we find that deference regimes are more like canons of statutory construction, applied episodically but reflecting deeper judicial commitments, than like binding precedents, faithfully applied, distinguished, or overruled. As a prescriptive matter, this study provides empirical support for pro posals to simplify the Supreme Court's continuum of deference regimes and to characterize the Court's deference decisions in the form of canons of statutory construction, and certainly not as precedents entitled to stare decisis effect. More broadly, the empirical analysis casts doubt on both the wisdom and the practicability of academic proposals to treat methodological opinions (such as Chevron) as precedents entitled to stare decisis. A jurisprudential reason for this skepticism, buttressed by the data in our study, is that statutory interpretation methodology (including deference) is inherently ad hoc and ought to be tailored to the circumstances of each statutory case, rather than bound to precommitted rules. Put another way, judicial deference to agency interpretations is a matter where bright-line rules will not necessarily yield greater predictability and law-like behavior among judges than context-saturated standards.