A federal constitution is usually

A federal constitution is usually written and rigid. A federal system of government is characterized by a division of power between the central government and the constituent units. The constitution of a federal state, therefore, spells out the powers and functions of the central and constituent units of the government. A written constitution is required in order to ensure that the powers and functions of the various arms of government are well defined and well understood. A rigid constitution is also necessary to prevent arbitrary changes to the constitution that could undermine the balance of power between the central government and the constituent units.