The Archibishop of Canterbury, Rowan Williams thinks the adoption of certain aspects of Sharia law in the UK "seems unavoidable". He said the UK has to "face up to the fact" that some of its citizens do not relate to the British legal system. Dr Williams argues that adopting parts of Islamic Sharia law would help maintain social cohesion. The BBC article said "Dr Williams noted that Orthodox Jewish courts already operated, and that the law accommodated the anti-abortion views of some Christians."
Williams' analogy is fundamentally false. Jews, Christians -- indeed Jains, Buddhists, Muslims and atheists -- can work for any change in British law they please. That is because only British law reigns supreme in Britain. But that is fundamentally different from advocating that British law share authority, however "constructively", with a rival and alternative legal system, like sharia law. The Anglicans, for example, can adopt any practice they freely choose. But that is fundamentally different from accepting that their religious authority is shared, for example, with the Church of the Latter Day Saints. Surely there is a difference, if Williams chooses to see it.