Constitutional law is a body of law dealing with the distribution and exercise of government power.
Not all nation states have codified constitutions, though all such states have a jus commune, or law of the land, that may consist of a variety of imperative and consensual rules. These may include customary law, conventions, statutory law, judge-made law or international rules and norms, and so on.
Constitutional laws may often be considered second order rulemaking or rules about making rules to exercise power. It governs the relationships between the judiciary, the legislature and the executive with the bodies under its authority. One of the key tasks of constitutions within this context is to indicate hierarchies and relationships of power. For example, in a unitary state, the constitution will vest ultimate authority in one central administration and legislature, and judiciary, though there is often a delegation of power or authority to local or municipal authorities. When a constitution establishes a federal state, it will identify the several levels of government coexisting with exclusive or shared areas of jurisdiction over lawmaking, application and enforcement.