In this Article, I report on an empirical examination of this question. My purpose is twofold. First, I developed and seek comment upon a new methodology for addressing this complex problem. Second, I applied this methodology to an existing database composed of D.C. Circuit remands of Environmental Protection Agency (EPA) rules under the “hard look” doctrine during the period 1985-1995. The results contrast sharply with various studies finding a significant degree of ideological, partisan voting on the D.C. Circuit. In Part I, I briefly review the prominent studies in this area. In Part II, I describe the methodology used in this study. Part III reports the results of my examination of whether D.C. Circuit decisions on substantive issues appear to be driven by the ideology of the judges on the panels or by attempts at principled decision-making.