'Deliberative Voting' describes a new kind of constitutional referendum. It is a 'deliberative democratic' innovation, which means that it aims to solve one of the oldest tensions of democratic lawmaking - between robust citizen involvement and careful deliberation. While citizen participation in lawmaking is desirable, it is also usually problematic. Few people outside of government have the time or expertise for well-informed, rigorous and reflective deliberation over the making of new laws. Normally we therefore delegate lawmaking to parliaments, whose members we expect will be suitably informed. Yet the solution of delegation is increasingly untenable - and undesirable - in the unique case of constitutional lawmaking. Leaving voters out of a process of reform now attracts convincing charges that both the process and the constitution it yields are illegitimate. Back in 1901, Australia thus became the second country, after Switzerland, to make constitutional referendums mandatory. Since then, referendums on key constitutional amendments in Europe and elsewhere have become commonplace.