The principle that ultimate political authority rests with the people, from whom government derives its legitimacy.
In more detail
Rousseau's Social Contract (1762) held that sovereignty belongs to the people, cannot be alienated and cannot be represented. Edmund Morgan traced how 'the people' became a political fiction in 17th- and 18th-century England and America. In practice it is exercised through elections, assemblies and referendums. It differs from parliamentary sovereignty, under which the legislature has the final word.