The literature on linguistic justice has evolved in parallel with that on national self-determination; or has simply dismissed the later. On the other hand, the normative literature on federalism has not yet provided us with consistent policy prescriptions for multilingual states. To remedy this gap in the normative literature, this paper offers a theory of language policy that is built into a republican theory of national self-determination. Building on two pillars of republican theory, the ideal of non-domination and the theory of the mixed government, the aim is to provide a normative theory of linguistic self-determination which avoids the reproduction of linguistic domination of permanent national minorities. The method consists of applying the system of checks and balances typical of the ‘mixed regime’ to principles of linguistic justice, such as territoriality and personality, which are usually defended individually as exclusive principles.