Questions as to who has what authority often lie at the heart of political debates, and answers to those questions normally stem from practical and moral considerations, from prior practices and from theories of criminal justice or of the just war.

In sociology, authority comprises a particular type of power. The dominant usage comes from functionalism and follows Weber in defining authority as power which is recognised as legitimate and justified by both the powerful and the powerless. Weber further sub-divided authority into three types:

• Traditional authority which simply derives from long-established habits and social structures. The right of hereditary monarchs to rule furnishes an obvious example.
• Charismatic authority. From time to time, people make extraordinary claims of heading a revolution of some kind (which is always against a well-established system of traditional or legal-rational authority). When followers take such claims seriously, this exemplifies charismatic authority: religious or political authority that does not flow from tradition or law, but instead thrives on the short-lived excitement of social change. The careers of Lenin, Martin Luther, Hitler, and Lech Walesa provide examples. Charismatic authority never lasts long (even when successful) and it inevitably gives way to either traditional or to legal-rational authority.
• Legal-rational authority depends for its legitimacy on formal rules, usually written down, and often very complex. Modern societies depend on legal-rational authority.

The Restoration (1814) marked a return to traditional authority, but now with elements of the legal-rational as well, at least until the ascent of Charles IX; his attempt to restore a more absolute monarchy brought on the July Revolution, which formally restored this balance of legal-rational and traditional in the form of a constitutional monarchy. The Revolution of 1848 passed rapidly into a legal-rational mode, falling ultimately to the Second Empire, which saw a blend of all three modes: the government Napoleon III retained a constitution of sorts and, in his person, he combined the Napoleonic charismatic claims with what was now a certain element of tradition, a Bonapartist dynasty to rival the Bourbons.

The complex pattern can be continued practically down to the present day, with a steadily diminishing role for traditional authority, except insofar as republicanism itself has become a tradition. In the Twentieth Century, France had at least two charismatic leaders, Philippe Pétain and Charles de Gaulle. The constitution of the Fifth Republic overtly a legal-rational system, was tailored specifically for the purpose of creating a presidency powerful enough that the charismatic leader de Gaulle would consent to accept it.

Within conflict theory, "authority" is used both in the same sense as Weber's functionalist definition above, and in a rather different sense which is based on the observation that power is almost never endorsed in a moral sense by those who do not have it, and therefore defines "authority" as power which is so institutionalised that it is largely unquestioned.

Obedience to authority seems thoroughly ingrained in most of the population: the Milgram experiment showed that over 60% of a sample of Americans demonstrated willingness to torture another person to death when given orders from an appropriate authority-figure. This experiment produced similar results when replicated in several other cultures.

See also: appeal to authority, power, trust, régime, law

Someone recognised as an authority on a particular subject apparently knows a great deal about that particular subject.