The word authority (derived from the Latin word auctoritas) can be used to mean the right to exercise power given by the State (in the form of government, judges, police officers, etc.), or by academic knowledge of an area (someone that can be an authority on a subject).
When the word authority is used in the name of an organization, this name usually refers to the governing body upon which such authority is vested; for example, the Puerto Rico Electric Power Authority or the Massachusetts Bay Transportation Authority. It is also the right to do something.
In government, the term authority is often used interchangeably with power. However, their meanings differ: while power is defined as "the ability to influence somebody to do something that he/she would not have done", authority refers to a claim of legitimacy, the justification and right to exercise that power. For example, while a mob has the power to punish a criminal, for example by lynching, people who believe in the rule of law consider that only a court of law has the authority to punish a criminal legally as the law says.
There have been several contributions to the debate of political authority. Among others, Max Weber, Hannah Arendt, Alexandre Kojève and Giorgio Agamben have provided some of the most remarkable texts.
In political philosophy, the jurisdiction of political authority, the location of sovereignty, the balancing of freedom and authority (cf. Cristi 2005), and the requirements of political obligations have been core questions from Plato and Aristotle to the present. Most democratic societies are engaged in an ongoing discussion regarding the legitimate extent of the exercise of governmental authority. In the United States, for instance, there is an apparent prevailing belief that the political system as instituted by the Founding Fathers should accord the populace as much freedom as reasonable, and that government should limit its authority accordingly.