The Nature of Supreme Court Power. By Matthew E. K. Hall. New York: Cambridge Univ. Press, 2011. 262 pp. $94.00 cloth.Merely Judgment: Ignoring, Evading, and Trumping Supreme Court. By Martin J. Sweet. Charlottesville and London: Univ. of Virginia Press, 2010. 240 pp. $35.00 clothMatthew E. K. Hall's The Nature of Supreme Court Power and Martin J. Sweet's Merely Judgment are impressive books considerably advance our knowledge about implementation and impact of Supreme Court decisions. Hall frames his study as a direct response to Gerald Rosenberg's thesis Court (and generally) 'can almost never be effective producers of significant social reform' (xiii; 160, quoting Rosenberg 2008: 422). Moreover, Hall argues, Rosenberg's view is emblematic of decided weight of scholarly authority on nature of Court's power. The Court is generally seen as a highly constrained and weak institution (13-15). By contrast, Hall finds that Court possesses remarkable power to alter behavior of [other] actors in a wide range of policy (160). Sweet wants to make a different argument. He claims political institutions enjoy considerable discretion in deciding whether and how to follow Court, because they can often defang would be plaintiffs (5). Obviously, both authors cannot be right. As is often case, as between Hall and Sweet, different theoretical approaches play a part in competing interpretations. Notwithstanding different approaches in play here, it seems to me for most part, Hall is right, and Sweet is wrong, although Sweet's study is well done and informative in many ways.Like Rosenberg, Hall is committed to social scientific positivism. Through an objective case selection method (27, and Appendix I), he pinpoints no less than 57 important cases decided between 1954 and 2006, which he then groups into 27 issue areas for purposes of impact analysis. Hall's conception of power, like Rosenberg's, is one-dimensional: 'A power relation, actual or potential, is an actual or potential relation between preferences of an actor regarding an outcome and outcome itself ' (7, quoting Nagel 1975). Hall's study, notwithstanding its incredible scope, is limited to seeking to observe whether Court changes behavior of other actors in cases in which it actually attempts to do so by striking down laws.The question is Under what conditions is Court powerful? (14). The independent variables are twofold: (1) the context of a decision, and (2) degree of popular opposition to a decision. The first of these brings us to Hall's great insight. Vast research demonstrates lower are generally faithful and reliable implementers of Court decisions (16). By institutional Hall means the distinction between Supreme Court rulings can and cannot be implemented by lower courts (5). He calls issues for which lower are primary in implementation process issues, and issues for which they are not issues. He codes every case as either vertical or lateral. For popular opinion, Hall relies exclusively on public opinion data. This elegant model thus yields a two-by-two framework for inquiry. Hall hypothesizes only very strong popular opposition in a lateral issue can defeat Court when it intends to alter behavior, and it follows Court can prevail over public opposition (even very strong opposition) in vertical cases, but not lateral ones. It then remains for Hall to specify relevant intended outcomes of Court's decisions, and to find good data can show us whether actors changed their behavior in response to them. Hall is well aware his analysis is shot through with interpretation and judgment calls. To his credit, he does not try to standardize his measures across cases, but rather clearly lays out his thinking about what research and information is available, which indicators or measures make most sense in a given context, and so on. …