Ideological Alliances on the Unites States Supreme Court:

Every year since 1957, the Harvard Law Review has published a matrix of the voting patterns of the previous Supreme Court term (Harvard Law Review, 1957). This matrix includes how often two justices vote together in cases as well as the total number of possible cases that any two justices could have voted together. From this tabular data it is possible to derive the normalized frequency with which any two justices vote together. However, information visualization techniques make these relationships more explicit. With information visualization techniques such as multi-dimensional scaling (MDS), the ideological alliances of the Court may be rendered as easy to comprehend spatial relationships. Justices voting together more frequently are rendered spatially more proximate to one another. Such visualizations serve to quickly convey the ideological landscape of the justices for any particular term of the Court. Equally as interesting is the ability to view these ideological landscapes over time. It is from these images, that one can observe changes in the Court's ideological composition-which factions are in the main and which are marginalized. Furthermore, one can observe interesting trends such as the distancing of justices that had once voted together with some regularity. One of the most famous examples is that of Harry Blackmun and Chief Justice Warren Burger. Close personal friends prior to their tenure on the Court, the two were initially dubbed the "Minnesota Twins" (Benton & Vahle, 2005). However, while on the Court, Blackmun moved ideologically apart from Burger. It was a time that also saw a chilling of their friendship. This distancing is clear from the data and serves to visually reinforce an oft told history. The Blackmun/Burger split illustrates the pedagological utility of information visualization in the legal context. It is a particularly timely utility given the legal academy's intense recent interest in empirical based legal research. In contrast to its traditional scholarship steeped in contemplative and doctrinal musings, the legal academy has become recently interested in method based and theory testing approaches to scholarship in which "quantitative or statistical analysis is a central component of the [research]" (George, 2006). As illustrated in the context of co-voting data, information visualization has a contribution to make to the legal academy's recent interest in quantitative legal studies. It is a role that stems from the ability of information visualization to make large quantitative datasets comprehensible for discovery, sense-making, and pedagogy.