This reminds me of the Millet system used under the Ottoman empire. The central government had very little direct involvement in what we would today call "personal law" or "social policy"; instead, these were organized into separate communities along religious lines. Muslims, Jews, and various Christian denominations each had their own sets of institutions.

A more modern example is Belgium, which has a kind of double federalism, where regional governments for Flanders and Wallonia have territorial jurisdiction, and community governments for the French-, Flemish-, and German-speaking populations have separate "social" jurisdiction.

In these cases, the social jurisdiction was determined by religious or linguistic affiliation, with only a handful of communities and very limited mobility among them. It would be very interesting to see such a system organized on a much more pluralistic and dynamic basis, in which people could charter their own communities and change their affiliations freely.