H.L.A. Hart, answered from the texts and cited to the page.
The rule of adjudication is the secondary rule that empowers individuals — courts, judges — to make authoritative determinations of the question whether, on a particular occasion, a primary rule has been broken.1 Such rules do more than identify who is to adjudicate; they also define the procedure to be followed.2 They do not impose duties in the manner of primary rules of obligation; rather, they confer judicial powers and a special status on judicial declarations about the breach of obligations.3
There is an intimate structural consequence worth noting. A system that has rules of adjudication is necessarily committed to a rule of recognition of at least an elementary kind, because courts empowered to make authoritative determinations of the fact that a rule has been broken cannot avoid being taken as making authoritative determinations of what the rules are.4
The rule conferring jurisdiction thus doubles as a rule of recognition, and judicial decisions become a source of law — though an imperfect one, since judgments may not be couched in general terms, and their use as authoritative guides depends on a somewhat shaky inference from particular decisions whose reliability fluctuates with the skill of the interpreter and the consistency of the judges.5
Most developed legal systems go further than the bare minimum. They have centralised the application of penalties, partially prohibited violent self-help by private individuals, and conferred on judges the exclusive power to direct the application of sanctions once a violation is established.6 Taken together with the rule of recognition and the rule of change, the rule of adjudication completes the union of primary and secondary rules that constitutes the heart of a legal system.7
The third supplement to the simple regime of primary rules, intended to remedy the inefficiency of its diffused social pressure, consists of secondary rules empowering individuals to make authoritative determinations of the question whether, on a particular occasion, a primary rule has been broken.The Concept of Law, p. 107
Besides identifying the individuals who are to adjudicate, such rules will also define the procedure to be followed.The Concept of Law, p. 107
they do not impose duties but confer judicial powers and a special status on judicial declarations about the breach of obligations.The Concept of Law, p. 107
a system which has rules of adjudication is necessarily also committed to a rule of recognition of an elementary and imperfect sort. This is so because, if courts are empowered to make authoritative determinations of the fact that a rule has been broken, these cannot avoid being taken as authoritative determinations of what the rules are.The Concept of Law, p. 107
judgments may not be couched in general terms and their use as authoritative guides to the rules depends on a somewhat shaky inference from particular decisions, and the reliability of this must fluctuate both with the skill of the interpreter and the consistency of the judges.The Concept of Law, pp. 107–108
they have supplemented the primary rules of obligation by further secondary rules, specifying or at least limiting the penalties for violation, and have conferred upon judges, where they have ascertained the fact of violation, the exclusive power to direct the application of penalties by other officials.The Concept of Law, pp. 107–108
if we stand back and consider the structure which has resulted from the combination of primary rules of obligation with the secondary rules of recognition, change and adjudication, it is plain that we have here not only the heart of a legal system, but a most powerful tool for the analysis of much that has puzzled both the jurist and the political theorist.The Concept of Law, pp. 107–108