Vetoes, deadlock and deliberative umpiring: Toward a proportionality doctrine for power-sharing constitutions

Abstract This article addresses power-sharing constitutions that include powers of veto wielded by discrete ethnonational groups. Such constitutional arrangements – seen, for example, in Northern Ireland and Bosnia – have often prompted severe deadlock, a problem that in turn threatens democratic functioning and raises the risk of renewed communal violence. We consider the use of ‘umpires’ of power-sharing constitutional systems to vet the use of vetoes and (potentially) to prevent their overuse or misuse. Power-sharing umpires are not uncommon in practice. However, as yet there is little scholarship evaluating how, in substance, power-sharing veto umpires should approach their task. Relying on deliberative democracy theory, the article outlines three forms of ‘deliberative agreement’ that, in principle, deeply divided groups may reach in the course of policymaking. It goes on to explain how existing proportionality doctrines drawn from federalism and rights cases can be imported into the power-sharing context to ‘scaffold’ these broad ideals. This approach, it is argued, may provide a more detailed, coherent and practically workable approach to umpiring power-sharing constitutions.