In resolving questions of statutory meaning, the lion’s share of Roberts Court opinions considers and applies at least one interpretive canon, whether the rule against surplusage or the presumption against state law preemption. This is part of a decades-long turn toward textualist statutory interpretation in the Supreme Court. Commentators have debated how to justify canons, since they are judicially created rules that reside outside the statutory text. Earlier studies have cast substantial doubt on whether these canons can be justified as capturing congressional practices or preferences; commentators have accordingly turned toward second-order justifications, arguing that canons usefully make interpretation constrained and predictable, supplying Congress with a stable interpretive background. Based on an extensive study tracking the use of over 30 interpretive canons in the first 10 years of the Roberts Court, this Article attempts to contribute evidence to the debate over canons.

The data raise substantial questions regarding stability and predictability. Despite a long tradition of use, some canons have essentially disappeared; meanwhile, the Court has created others out of whole cloth. In addition, application is erratic. The Roberts Court Justices have declined to apply even the most widely engaged canons 20–30% or more of the time, often for difficult-to-anticipate reasons; some well-known canons, such as the rule of lenity and the presumption against preemption, were applied roughly at a 50–50 rate. The story is worse in the many cases in which multiple canons are considered. Based on these and other findings, this Article accordingly argues that predictability and stability arguments cannot supply a firm foundation for canon use. The study also reveals troubling mismatches between canons actually in use and congressional staff acceptance of canons. The Article concludes by suggesting some future directions for investigation and reform.