Building on his earlier work on judicial decisionmaking in the D.C. Circuit, Professor Revesz now examines whether this court’s ideological divisions are affected by changes in the composition of the political branches: the two chambers of Congress and the Presidency. Thus, he seeks to test empirically the plausibility of positive political theory models of adjudication, which posit that judges act in an ideologically “strategic” manner. The data set developed for this study consists of all cases decided by the D.C. Circuit between 1970 and 1996 that challenged the health-and-safety decisions of twenty federal agencies. While the study confirms the author’s earlier findings of ideological voting in the D.C. Circuit, it does not find any statistically significant evidence that these ideological divisions are affected by the party controlling Congress or the Presidency. This finding invites a reassessment of the leading positive political theory accounts of the effects of judicial review of administrative action.