A growing body of research applies behavioral approaches to the study of international law, mainly by studying convenience samples of students or other segments of the general public. Alongside the promises of this agenda are concerns about applying findings from non-elite populations to the people, and groups of people, charged with most real-world decision-making in the domain of law and governance. This concern is compounded by the fact that it is extremely difficult to recruit these actual decision-makers in a way that allows for direct study.

Behavioral approaches have been successful in challenging the rational actor model of international legal analysis and supplementing that model with empirical evidence. Yet observing a set of features about the world requires ignoring or bracketing others. Behavioral approaches retain their own inevitable blind spots, which are not necessarily products of flawed experimental design, but stem from the paradigmatic traits of these approaches. These blind spots derive from an emphasis on methodological individualism, positivism, and experimentation. This emphasis may obscure the social aspects of international legal decision-making. For example, behavioral approaches to international law often use experimental data to describe cognitive tendencies. In doing so, these approaches may not seek and likely will not have tools to discover the meaning of a state action, or the human actions that produce that state action. That latter inquiry requires “historical, ethnographic and other sociological methods that analyze social life outside of the experimental setting.” In sum, behavioral approaches pursue both theoretical and empirical concerns different from those pursued in an interpretive mode of meaning-making.

Boilerplate treaty provisions are identical or nearly identical terms that reflect settled legal language in treaties with different states parties. They are often taken from model treaties or templates and reflect non-negotiated “default rules” or rules that emerged in international practice, rather than individually tailored provisions adapted to the circumstances of the specific contracting parties. Although widespread in international economic law, boilerplate provisions have not been subject to much scrutiny, unlike their distant cousins in contract law. This essay highlights drivers and functions of boilerplate in international economic law along with core expectations from rationalist and behavioral approaches. Boilerplate can provide efficient solutions to international economic problems, for instance by reducing contracting costs, and provide bargaining leverage in asymmetric negotiations. Yet boilerplate can also result in unintended and unwanted consequences, such as when drafters fail to carefully consider “default” provisions or have an excessive preference for the status quo.

While Articles 31 and 32 of the Vienna Convention on the Law of Treaties (VCLT) prescribe the rules of interpretation for international treaty law as “disciplining rules,” the rules of interpretation themselves are understudied from a cognitive psychology perspective. This is problematic because, as Jerome Frank observed, “judges are incurably human,” like everybody else. I submit that behavioral approaches could provide insights into how biases and heuristics affect the way judges and other interpreters use the VCLT rules.

The use of nudges—“low-cost, choice-preserving, behaviorally informed approaches to regulatory problems”—has become quite popular at the national level in the past decade or so. Examples include changing the default concerning employees’ saving for retirement in a bid to encourage such saving; altering the default about consent to posthumous organ donation to increase the supply of organs for transplantation; and informing people about other people's energy consumption to spur them to reduce theirs. Nudges are therefore used to promote the welfare of the people being nudged, and of society at large. However, the use of nudges has sparked a lively normative debate. When turning to the international arena, new arguments for and against nudges can be raised. This essay focuses on the normative aspects of using nudges in the international arena.