A number of intractable geo-political situations illustrate the need for more flexible and innovative approaches to sovereignty. Classic examples are Jerusalem (and more broadly Palestine) and Northern Ireland, where religious and/or ethnic dimensions increase the difficulty of any negotiated solution.
The most striking example was the Anglo-French Condominium of the New Hebrides, established in 1906, which acquired independence in 1980. The administration was structured into three parts: the French National Service, the British National Service and the Condominium (Joint) Departments. The UK and France were each responsible for their own citizens and for indigenous people who chose to be ressortissants of either power, although the indigenous were not permitted to claim either French or UK nationality. In practice this resulted, in the same territory, in two official languages, two police forces, and three public services. The island of St Maarten in the Caribbean is jointly governed by France and the Netherlands, although the island is geographically divided. Andorra is a co-principality established in 1278, currently under the suzerainty of the President of France and the Spanish Bishop of Urgel, although since 1993, these positions have become purely honorary.
Where more conventional efforts to conflict situations have failed over many years, there is a strong case for exploring formulas for joint sovereignty over a a common territory. Options might include choice of nationality, dual nationality, attribution of certain functions to one system of government and the remainder to another. Such formulas could extend to voting and taxation systems.