Ruggiero provides a systematic evaluation of the 'interdependent nature' of judicial power within three federal systems. She seeks to answer the question: Why are some high courts more powerful than others? By integrating strategic assumptions about the behavior of courts and other political actors and by employing a comparative, historical analysis of court policy-making and legislative responses to said policy-making, Ruggiero tests and refines concepts of court influence as 'interdependent'. She finds that the influence of high courts and their decisions are shaped both by 'intrinsic' institutional features, as well as the 'extrinsic' environment (political and federalist).