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IntroductionThis paper examines a spatial model of roll call voting on Supreme Court nominations from John Harlan (1955) to Anthony Kennedy (1988). We approach roll call voting from much the same perspective as proponents of the new institutionalism who have adapted the spatial theory of voting to the roll call setting (Krehbiel and Rivers 1988). We explain below why we believe this approach is particularly promising. But we address the questions raised in recent roll call studies and the literature on representation in legislatures more broadly by considering the impact of constituent desires, interest group pressures, presidential power, and the personal ideologies of legislators on roll call votes. We focus on voting on Supreme Court nominees, which supplies a tractable setting for examining these questions. The model builds on our previous work (Cameron, Cover, and Segal 1990), in which constituency ideology is measured inferentially using scores developed by the Americans for Democratic Action (ADA). Our new model represents an This content downloaded from 128.255.6.125 on Mon, 20 Jun 2016 15:21:02 UTC All use subject to http://about.jstor.org/terms A SPATIAL MODEL OF ROLL CALL VOTING 97effort to measure constituency influence more directly and to purge the ADA scores of senators' personal ideologies. In this model selected state-level presidential election results are used to measure constituency ideology. We then add an explicit measure of the effect of senators' personal ideologies in addition to the purified constituency measure of the previous model. This model further extends our original work by offering a more complete specification of how the president affects the confirmation process and by incorporating interest group activity into the model as a factor that influences senators' votes.
Ideology, Constituents, and Roll Call VotingWithout slighting other approaches, we start our examination of roll call voting with those studies t...