Devolution differs from federalism in that the devolved powers of the subnational authority may be temporary and are reversible, ultimately residing with the central government. Thus, the state remains "de jure" unitary. Legislation creating devolved parliaments or assemblies can be repealed or amended by central government in the same way as any statute. In federal systems, by contrast, sub-unit government is guaranteed in the constitution, so the powers of the sub-units cannot be withdrawn unilaterally by the central government (i.e. without the consent of the sub-units being granted through the process of constitutional amendment). The sub-units therefore have a lower degree of protection under devolution than under federalism.