<P> To some extent a group of states which do not constitute a federation as such may by treaties and accords give up parts of their sovereignty to a supranational entity . For example, the countries constituting the European Union have agreed to abide by some Union - wide measures which restrict their absolute sovereignty in some ways, e.g., the use of the metric system of measurement instead of national units previously used . </P> <P> Constitutions usually explicitly divide power between various branches of government . The standard model, described by the Baron de Montesquieu, involves three branches of government: executive, legislative and judicial . Some constitutions include additional branches, such as an auditory branch . Constitutions vary extensively as to the degree of separation of powers between these branches . </P> <P> In presidential and semi-presidential systems of government, department secretaries / ministers are accountable to the president, who has patronage powers to appoint and dismiss ministers . The president is accountable to the people in an election . </P> <P> In parliamentary systems, Cabinet Ministers are accountable to Parliament, but it is the prime minister who appoints and dismisses them . In the case of the United Kingdom and other countries with a monarchy, it is the monarch who appoints and dismisses ministers, on the advice of the prime minister . In turn the prime minister will resign if the government loses the confidence of the parliament (or a part of it). Confidence can be lost if the government loses a vote of no confidence or, depending on the country, loses a particularly important vote in parliament, such as vote on the budget . When a government loses confidence, it stays in office until a new government is formed; something which normally but not necessarily required the holding of a general election . </P>

What is the purpose of constitution in a democratic country