A constitution is a system, which establishes the rules and principles by which an organisation is governed. In the case of nations, this term refers specifically to a national constitution, which defines the nation's political principles and establishes the power and duties of each government. Most national constitutions also guarantee certain rights to the people. This is commonly called the Bill of rights. A Bill of Rights is a statement of certain rights that citizens and/or residents of a free society have (or ought to have). In some jurisdictions, the Bill of Rights is entrenched in the constitution of that nation-state. When embedded in the constitution, it can prescribe the limits of power the government has to intervene in the lives of its citizens.