Locating Supreme Court Opinions in Doctrine Space
41 Pages Posted: 7 Aug 2009 Last revised: 24 Sep 2009
Date Written: August 4, 2009
This paper develops a scaling model to estimate opinion locations and justice ideal points along a common, continuous dimension using the citations between opinions as data. We assume that each opinion has a fixed location in this doctrine space and that the probability of a citation that decreases in distance between two opinions. This proximity citation model is applied to original datasets of citations in search and seizure and freedom of religion opinions written between 1953 and 2006. The resulting estimates of opinion location are used to evaluate theories of Supreme Court bargaining and opinion writing. We find empirical support for theoretical models that predict the majority opinion will fall at the ideal point of the median member of the majority coalition. Given the centrality of theories of judicial policymaking to various substantive problems in political science, the method of scaling opinions developed in this paper can facilitate future research.
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