Why do judges craft vague opinions if these are less likely to be implemented? In a game-theoretic model, Staton and Vanberg (2008) argue that opinion vagueness is a function of judge’s policy preferences and their fear of potential noncompliance by the legislature. Yet, the court’s ability to use vagueness ultimately depends on their level of public support. I empirically test the implications of their model in a comparative study of two constitutional courts in Germany and France, analyzing novel data on opinion vagueness obtained by neural networks. My findings confirm that a court’s public support is indeed the key factor for explaining how courts strategically use vagueness. The German Federal Constitutional Court, a court with high public support, uses vagueness primarily to take advantage of the policy expertise of other policy makers and to strategically pressure the legislature. In contrast, the French Conseil Constitutionel, a court with low public support, uses vagueness as a “defensive mechanism” to hide noncompliance from public view. My results therefore imply that current models of judicial behavior underestimate the full extent of strategic behavior of courts.