Do states take court decisions into account when formulating policies? If so, how do they process new judicial input and make policies in response to them? While self-interest and incentives are the usual elements involved in a rational choice explanation of policymaking, behavioralist scholarship casts doubt on whether decisionmakers are able to identify and pursue their interests in a rational manner. We draw on rational and behavioral approaches to formulate different expectations about the process of policymaking and updating in the context of maritime delimitation. We focus on how states formulate policies about the appropriate method of maritime delimitation given relevant decisions of the International Court of Justice. Using a dataset of continental shelf delimitation policies, we find evidence that at least some states change policies in line with court decisions. However, we are unable to distinguish between mechanisms consistent with rational choice and those suggested by behavioralism. We discuss why behavioralist explanations of policymaking processes are difficult to test in a large-N setting. Moreover, we discuss why additional evidence from interviews also proves insufficient, notably due to actors’ tendency to rationalize state policies. We end by suggesting how these problems can be addressed in future research.