Despite the importance of the Senate role in the confirmation of Supreme Court justices, knowledge of the factors affecting the votes of senators is sparse. This project attends to this deficiency by developing a theory of roll call voting that portrays senators as operating primarily in the interests of their consitutents. Senators, however, have their own personal preferences about the composition of the Supreme Court. In addition, presidents can bring rewards and punishments to bear on senators in attempting to influence their vote. Accordingly, senators must weigh the costs and benefits of 1) supporting the opposing constituent desires, 2) pursuing their own policy goals, and 3) supporting or opposing the president's nominee. To assess the weight senators put on the various actors seeking to influence their vote on confirmation, this project develops a testable model of how public opinion, the perceived ideology of the nominee, and the political circumstances surrounding the nomination came together to influence a senator's vote. Components of the model include the popularity and power of the president, the ideological preferences of both senators and their constituents, the ideology and qualifications of the nominee, and the importance of the open seat on the Court. The theory is tested on the 2,214 individual confirmation votes from Tom Clark (1949) through Anthony Kennedy (1988). The chief technique used to test the theory is probit analysis, an approach that permits the estimation of how important various factors are in determining whether or not a senator votes to confirm a nominee's appointment to the Court. The research improves on earlier investigations in several respects. It focuses on a significant period of change for the Court, not just on the events surrounding a particular nomination. It attempts to explain the votes of individual senators, not just the Senate as a whole. It casts its net widely to include not only controversial nominations but noncontroversial ones as well. It takes seriously the notion that a nominee's ideology and qualifications for the Court may prove to be major influences on a senator's confirmation vote. In exploring the role that these factors play as vote determinants, the research develops measures for perceived ideology and qualifications. The project assesses these factors through a systematic content analysis of major newspaper editorials on each nominee. The theory underlying the model tested in the project - - "principal- agency theory" - - has proved to be useful in numerous other contexts. The theory has not previously been developed, however, to explore how institutional and political circumstances actually work to affect a legislator's voting decision. Thus, the theory itself should be enriched by this novel extension and application. The research, therefore, has broad theoretical payoffs as well as helping us understand better the dynamics of a major part of the confirmation process.
