Legitimacy is both a specific legal concept, meaning that something is lawful, and at the same time and amorphous psychosociological concept referring to an important element in the social glue that holds institutions together. The quality of an administration that has come to power through free elections or established constitutional procedures. Thus a government imposed by military force may lack legitimacy. A characteristic of the exercise of political power when that power is believed to be in accordance with certain principles and practices. Political science is primarily concerned with the beliefs and practices actually present within a system, and so uses 'legitimacy' principally in the descriptive sense.
Legitimacy is crucial for the operation of government, and for the survival of the political system.
All government depends on some belief in its right to exercise power, even though that belief may never be unanimous and may sometimes be limited to key elements of the state apparatus. Governments will therefore seek to justify the form and content of their rule by reference to those principles that seem most cogent. The production of appropriate beliefs, whether by the conscious creation of ruling groups or by unintended social processes, is referred to as 'legitimation'. In this case, such organization is deriving its legitimacy from natural justice, just as a monk or clergy making reference to the religious scripts or a Judge from the High Court interpreting Constitution. On the otherhand, governments in democracies, based on their popular mandate, may derive its legitimacy from popular opinion and demand the public to obey a certain set of rules.