Hidden figures: how legal experts influence the design of international institutions.

Whose preferences influence the design of international institutions? Scholarship on the legalization of international politics and creation of international legal institutions largely adopts a state-centric perspective. Existing accounts, however, fail to recognize how states often delegate authority over institutional design tasks to independent legal experts whose preferences may diverge from those of states. We develop a principal-agent (PA) framework for theorizing relations between states (collective principals) and legal actors (agents) in the design process, and for explaining how legal actors influence the design of international institutions. The legal dimensions of the PA relationship increase the likelihood of preference divergence between the collective principal and the agent, but also create conditions that enable the agent to opportunistically advance its own design preferences. We argue that the more information on states' preferences the agent has, the more effectively it can exploit its legal expertise to strategically select and justify design choices that maximize its own preferences and the likelihood of states' acceptance. Our analysis of two cases of delegated institutional design concerning international criminal law at the United Nations and the African Union supports our theoretical expectations. Extensive archival and interview data elucidate how agents' variable information on states' preferences affects their ability to effectively advance their design preferences. Our theory reveals how independent legal experts with delegated authority over design tasks influence institutional design processes and outcomes, which has practical and normative implications for the legalization of international politics.