decisionType=1: Cases the Court decides by a signed opinion. Note that for the 1946 terms to present, decisionType=1 cases are those that the Court decided by a signed opinion and in which it heard oral arguments. This is true for the 1791–1945 terms too. When both these conditions are met, the case is coded as decisionType=1. But the second condition—oral argument—is no longer necessary for a decisionType=1 classification. That’s because the dates of oral argument were not reported for many cases that were likely argued (if only because the reporter noted, “After argument…”). We are working to locate these (many) missing dates and would appreciate any leads from users.

Jettisoning the oral argument requirement also means that there are many cases that were probably not orally argued but that are included as decisionType=1 cases because a justice is listed as delivering the opinion of the Court. For users that want to examine cases we know for sure were orally argued, we suggest selecting on dateArgument—with the important caveat that you will miss cases that were likely argued but are lacking a date.

decisionType=2: Cases decided with an opinion but without hearing oral argument; i.e., per curiam opinions. In the legacy data, decisionType2 cases include cases in which the Court (or reporter) did not use the term “per curiam” but rather “The Court [said],” “By the Court,” or “By direction of the Court.” If these cases identify the author of the opinion, we code an opinion writer.

decisionType=4: Decrees. This infrequent type of decision usually arises under the Court’s original jurisdiction and involves state boundary disputes. The justices will typically appoint a special master to take testimony and render a report, the bulk of which generally becomes the Court’s decision. The presence of the label, “decree,” distinguishes this type of decision from the others.

decisionType=5: Cases decided by an equally divided vote. When a justice fails to participate in a case or when the Court has a vacancy, the participating justices may cast a tie vote. In such cases, the Reports merely state that “the judgment is affirmed by an equally divided vote” and the name of any nonparticipating justice(s). Their effect is to uphold the decision of the court whose decision the Supreme Court reviewed.

decisionType=6: This decision type is a variant of decisionType=1 cases. It differs from type 1 in that no individual justice’s name appears as author of the Court’s opinion. Instead, these unsigned orally argued cases are labeled as decided “per curiam” The difference between this type and decisionType=2 is the occurrence of oral argument in the former but not the latter. In both types the opinion of the Court is unsigned.

decisionType=7: Judgments of the Court. This decision type is also a variant of the formally decided cases. It differs from type 1 in that less than a majority of the participating justices agree with the opinion produced by the justice assigned to write the Court’s opinion. Except for those interested only in the authors of the opinions of the Court, decisionType=7 should be included in analyses of the Court’s formally decided cases. See also the notes under decisionType=1.

The database does not contain all of the non-orally argued per curiam decisions (decisionType=2). The Reports contain large numbers of brief, non-orally argued per curiam decisions. The database includes only those for which the Court has provided a summary, as well as those without a summary in which one or more of the justices wrote an opinion.

Along similar lines, the database also does not contain memorandum decisions or “back-of-the-book” U.S. Reports cases with the exceptions of, first, volumes 131 and 154. In these volumes, the reporters included (in the Appendices) cases previously omitted or “not hitherto reported in full.” Second, we are trying to include all orally argued cases in the back-of-the-book (the Database already contains “front-of-the-book” orally argued cases). All decisionType=5 orally argued cases, even if in the back of the book, already have been entered. We are in the process of adding decisionType=6 back-of-the-book cases. In the vast majority of these, the Court dismissed the case with a one-line sentence.