By Duina, Francesco, and Tobias Lenz

Many observers of the European Union (EU) argue that economic integration has generated a ‘democratic legitimacy deficit’. They point to six problematic institutional mechanisms influencing the ‘input’, ‘throughput’, and ‘output’ dimensions of EU policy-making. Despite recent calls not to consider the EU as a sui generis case of integration, scholars have yet to investigate in a systematic fashion whether other regional economic organisations (REOs) may also be experiencing a democratic legitimacy deficit. In this article, we examine whether the six deficit-causing mechanisms purportedly present in the EU case are at work in the most important REOs in the world. We develop an operationalisation of these mechanisms and find those REOs to have, on the whole, low levels of legitimacy, which tend to be more pronounced in ‘input’ and ‘output’ than in ‘throughput’, though important differences exist across REOs. We reflect on the EU case in light of our comparative evidence. We conclude by outlining an agenda for future research on the democratic legitimacy of REOs and beyond.