We construct the complete network of 26,681 majority opinions written by the U.S. Supreme Court and the cases that cite them from 1791 to 2005. We describe a method for using the patterns in citations within and across cases to create importance scores that identify the most legally relevant precedents in the network of Supreme Court law at any given point in time. Our measures are superior to existing network-based alternatives and, for example, offer information regarding case importance not evident in simple citation counts. We also demonstrate the validity of our measures by showing that they are strongly correlated with the future citation behavior of state courts, the U.S. Courts of Appeals, and the U.S. Supreme Court. In so doing, we show that network analysis is a viable way of measuring how central a case is to law at the Court and suggest that it can be used to measure other legal concepts.

W e posit that Supreme Court oral arguments provide justices with useful information that influences their final votes on the merits. To examine the role of these proceedings, we ask the following questions: (1) what factors influence the quality of arguments presented to the Court; and, more importantly, (2) does the quality of a lawyer's oral argument affect the justices' final votes on the merits? We answer these questions by utilizing a unique data source--evaluations Justice Blackmun made of the quality of oral arguments presented to the justices. Our analysis shows that Justice Blackmun's grading of attorneys is somewhat influenced by conventional indicators of the credibility of attorneys and are not simply the product of Justice Blackmun's ideological leanings. We thus suggest they can plausibly be seen as measuring the quality of oral argument. We further show that the probability of a justice voting for a litigant increases dramatically if that litigant's lawyer presents better oral arguments than the competing counsel. These results therefore indicate that this element of the Court's decisional process affects final votes on the merits, and it has implications for how other elite decision makers evaluate and use information.

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Why do justices author or join separate opinions? Most attempts to address the dynamics of concurrence and dissent focus on aggregate patterns across time or courts. In contrast, we explain why an individual justice chooses to author or join a separate opinion. We argue that separate opinions result from justices' pursuit of their policy preferences within both strategic and institutional constraints. Using data from the Burger Court (1969 to 1985 terms), we estimate a multinomial logit model to test the influence of these factors on justices' decisions to join or author a regular concurrence, a special concurrence, or a dissent, as opposed to joining the majority opinion. Our results show that this choice reflects the justices' conditional pursuit of their policy preferences. We also disentangle the decision to join or author separate opinions, and we find that the latter decision is also influenced by the time remaining in the Court's term.

We examine the presidential nominees' choice of running mate in each election since 1940, when Franklin Roosevelt established a precedent by naming his own. To analyze the 22 choices made from the pool of 127 serious possibilities, we employ a discrete choice model. We find that the presidential nominee's choice is explained primarily by the size of the prospective vice president's state, by whether the running mate finalist was a rival for the nomination, and by the balance in age for the ticket.