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The remarkable rise in dictionary usage by the Supreme Court since themid-1980s has been a subject of considerable scholarly and media interest. Wepublished an article in November 2013 that explored the Court’s new dictionary culture in depth from empirical and doctrinal perspectives. In a Yale Law Journal Note one year later, John Calhoun embraced some of our findings, criticized others, and—importantly—broadened the inquiry to identify asizeable gap in overall frequency of citation to dictionaries between the Supreme Court and the federal courts of appeals.

This gap in dictionary usage is our primary focus here. Previously we analyzed nearly 700 Supreme Court cases decided between 1986 and 2011, taken from three fields that together comprise substantial portions of the Court’s statutory docket: labor and employment law; business and commercial law; and criminal law.3 In this Essay, we examine dictionary use by federal courts of appeals in these same cases before the Supreme Court granted certiorari and reviewed them. Our analysis encompasses majority opinions from the circuit courts in 109 cases where the Supreme Court subsequently made affirmative use of dictionaries and in 106 cases where the Court’s decisions did not make use of dictionary definitions.

We find that circuit courts cited to dictionaries in only one-sixth of the cases where the Supreme Court went on to use dictionaries after granting certiorari and in only about one of every nineteen cases in which the Court did not use dictionaries. The frequency of circuit court citation increased from the early Rehnquist Court period to the late Rehnquist and early Roberts Court years, but over that same period the gap between appeals court and Supreme Court references to dictionaries grew by substantial amounts. Further, when dictionary definitions were invoked, Supreme Court justices relied on those definitions to help justify the result (not simply as citations in dicta) over four fifthsof the time—twice as often as circuit court judges did when they cited dictionaries. Additional findings, reported below, support our conclusion that there are striking differences between the dictionary cultures in the Supreme Court and the courts of appeals.

We begin by setting forth brief background regarding how our approach to analysis of dictionary use differs from Calhoun’s. Contrary to Calhoun’s assertions, there are no direct disagreements between us when our respective Supreme Court datasets are properly compared. We then describe our empirical approach to the courts of appeals data and present our findings, which relate to the basic gap in frequency of usage and reliance. We also describe some finer-grained observations regarding number and types of dictionaries used, and how often the circuit court judges and the justices define the same word in the same case. Finally, we suggest possible reasons why the Supreme Court uses and relies on dictionaries so much more often than circuit courts, and we outline plans for further research in this area.

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