Legitimacy in simple sense is derivative of legitimate which means allowed by the law or rules or something which is able to be defended with reasoning. In political sense it is the property that a regime‟s procedures for making and enforcing laws are acceptable to its subjects. Legitimacy is an important ingredient of authority along with power. Legitimacy of a rule or decision implies that the members of society treat that rule or decision as beneficial to society as well as to themselves. So they willingly tend to abide by it. Use of force or coercion or sanctions may be resorted to only when legitimacy fails to work. Legitimacy is based on respect and willing compliance.
Political science is indebted to Max Weber for application of the term in the manner that Legitimacy constituted the basis of very real differences in the way power was exercised. Liberal thinking requires justification of power. It does not take authority granted or something invincible. In Weberian description there are three broad grounds for exercising authority, based on: tradition, charisma, and rational legal authority. All three depends on certain belief in the legality of enacted rules and right of those in positions of authority to issue commands. Weber advocated that in modern democratic societies with prevalence of rule of law obedience is owed not to a traditionally sanctioned person or a charismatically qualified leader, but to the legally established impersonal order. It extends to the persons occupying a public office by virtue of the legality of their commands. He demonstrated limitations over such authority when he stated that such authority is confined to the scope of the office and cannot be used in capricious of self- interested way.
S. M. Lipset raises the concept to different height when he discussed the capacity of the political system to engender and maintain the belief that the existing political institutions are the most appropriate ones for the society. He underlined the acceptance of the political system by the plural fabric of the society. He argues that Western nations have had to face three difficult and potentially destabilizing issue: the place of the church of various religions within the nations; the admission of the working class to full economic and political rights; the continuing struggle over the distribution of the national income.
In this sense presently globalization poses further challenges to the legitimacy of the political system in general. Those groups who claim certain specific identities do not accept the legitimacy of the territorial boundaries of the nation-states. Quebecs in Canada, dissolution of Yugoslavia, and dissent in Northern Ireland are few of many examples that markedly emphasise this phenomena. In other way the issue of legitimacy also arises in relation to new types of political formation such as European Union which is struggling to meet the legitimacy criteria on political front among the population of its member nations.
The importance of Legitimacy can be emphasized in the words that the ability to issue commands which are seen as binding because they are legitimate is one of the central pillars of a stable political order.
David Easton refers to three types of legitimacy; ideological legitimacy, structural legitimacy , and personal legitimacy.
Ideological legitimacy is based on the moral convictions about the validity of the regime and incumbents of authority. When the source of legitimacy is the ideology prevailing in the society, it is called ideological legitimacy.
Structural legitimacy is based on an independent belief in the validity of the structure and norms and incumbents of the authority.
Personal legitimacy is based on the belief in the validity of the incumbents of authority roles to the authority roles themselves. The belief in the validity of authorities is based on their personal qualities.