Party Competition, Populism, and Sovereignty Transfer to International Organizations

Domestic contestation has become a defining feature of contemporary international cooperation, yet systematic evidence on how states transfer sovereignty to international organizations remains limited. This paper introduces a new global dataset designed to address this gap by shifting the analytical focus from international organizations to their member states. It presents the conceptual logic, measurement strategy, and analytical scope of the Sovereignty Transfer (STR) dataset. STR covers 178 countries over the period 1970–2019 and conceptualizes sovereignty transfer as the accumulation of formal-legal constraints on national policy autonomy arising from membership in international organizations. These constraints are measured across four stages of the policy cycle agenda-setting, decision-making, implementation, and enforcement and are disaggregated across 25 policy fields, allowing for the identification of variation both across countries and within states across domains that differ in political sensitivity. The dataset is constructed by reconfiguring and extending existing measures of international authority, enabling a systematic assessment of sovereignty transfer at the state-year-policy field level. By integrating STR with party competition data, the paper enables large-N analysis of how party positions and issue salience are associated with patterns of sovereignty transfer.