Although scholars increasingly acknowledge a contemporaneous relationship between public opinion and Supreme Court decisions, debate continues as to why this relationship exists. Does public opinion directly influence decisions or do justices simply respond to the same social forces that simultaneously shape the public mood? To answer this question, we first develop a strategy to control for the justices' attitudinal change that stems from the social forces that influence public opinion. We then propose a theoretical argument that predicts strategic justices should be mindful of public opinion even in cases when the public is unlikely to be aware of the Court's activities. The results suggest that the influence of public opinion on Supreme Court decisions is real, substantively important, and most pronounced in nonsalient cases.In the final analysis it is simply not clear whether the Court responds to public opinion, or shapes public opinion, or whether it responds to the same sort of factors that themselves shape public opinion. (Gibson 1990, 290) D oes public opinion influence Supreme Court decisions? The answer to this question holds implications for the debate over how justices decide cases, the sources of the Court's legitimacy and how that may be threatened, and the extent to which the Court acts as a majoritarian or countermajoritarian institution. Yet, despite the theoretical and normative importance of understanding the relationship between public opinion and the Supreme Court, Gibson's (1990) words still resonate. A vast literature documents an empirical association between public opinion and judicial decisions (Flemming, Bohte, and Wood 1997; Giles, Blackstone, and Vining Christopher J. Casillas is a Ph.D. Candidate in the for helpful comments. Data needed to replicate the analyses presented in this article can be found at http://dvn.iq.harvard.edu/dvn/dv/Enns.