Durkheim's work is thus addressed primarily to the question of what law is for, what is the function of law and punishment. In his analysis of different kinds of power, the German sociologist Max Weber addressed the question of what law is, or should be, like in modern society. He showed the importance of law as a system of rules, consistently applied, with auth¬ority vested in persons only when they are acting in an appointed role. Thus, judges can only pronounce sentence when sitting in a duly consti¬tuted court; as private citizens (doing the shopping, walking the dog) they have no more power than anyone else to penalize someone they may come across committing an offence. Weber's description of the characteristics legal systems must display to command respect in modern societies finds a contemporary echo in questioning of the degree of legitimacy granted by a population to its penal system - the degree to which the criminal justice and penal systems of a country are felt by the majority of its citizens to be fair and reasonable, to be staying within proper limits in their exercise of power. Contemporary sociologists of punishment talk of a 'crisis of legitimacy' (Cavadino and Dignan 1992: Chapter 1), and concern with issues such as 'disparity' in sentencing (giving different sentences for similar offences) echoes Weber's emphasis on the importance of rule-governed rationality in modern legal systems.