The origins of the Privy Council may be found in the medieval king's Council. The great lords and prelates were regarded as the king's natural counsellors; they met from time to time to debate matters of policy in the Great Council or in Parliament, where they came to form the House of Lords. The continuing task of administration, however, required a more compact and permanent body of advisers drawn from the chief ministers of state (the Chancellor, the Treasurer and the Keeper of the Privy Seal), a few bishops, secular peers and senior household officials, and occasionally judges, lawyers and other laymen. This body had its antecedents in the undifferentiated curiaregis. With the emergence of the medieval departments and courts discharging particular functions or procedures of the curia, such a body of counsellors meeting frequently to advise the king on day to day problems of government took on a distinct identity and came to be known as the King's Council and, unofficially from the fourteenth century and more formally from the fifteenth century, as the Privy Council. Despite attempts by Parliament and the courts to delimit its powers, these remained imprecise ranging from important matters such as foreign policy and the maintenance of public order to relative trivia such as the repair of sea walls and the payment of royal bills. Under the Tudors the Privy Council emerged as the central organ of government and even after the rise to power of the Tudor secretaries most royal government was conducted in its name.
The Council enjoyed powers which would now be characterised as political, administrative, legislative and judicial, but which were only gradually differentiated. The primary function was that of advising the king on the government of the realm and in the formulation of royal foreign and domestic policy. It was natural that the king should remit much business to the Council to determine at its discretion and this practice was fostered as the chief ministers and the Council gradually ceased to be constantly attendant upon the itinerant king. In this way the Council acquired an administrative role and, in particular, special responsibility for royal grants of land, rights or pardons and for matters affecting royal revenue. The execution of Council decisions was carried out by virtue of Council bills or warrants directed to the appropriate department of state.
The legislative functions of the Council were not at first sharply differentiated from those of Parliament, but during the fourteenth century parliamentary statutes tended to be reserved for the more solemn legislation, while the Council issued ordinances and proclamations implementing, supplementing or, on occasion, suspending statute law or dealing with matters of a lesser, temporary or prerogative character.
The Council's judicial functions consisted of hearing petitions to the king and acting as a judicial tribunal in cases where the common law courts afforded no remedy or were ineffective, for instance in dealing with civil disorder. These functions were to some extent formalised from the fourteenth century, by the practice of referring certain petitions and cases to the Chancellor as a member of the Council, resulting in the equity jurisdiction of Chancery. Cases of treason, rebellion, civil disorder, heresy, ecclesiastical presentations, cases affecting the right of the crown and other matters of political importance remained within the purview of the Council itself. The Council determined few cases itself, but lent its authority to the courts to which it remitted cases. Some cases were remitted to the common law courts, but more commonly special commissions of oyer and terminer, of trailbaston and of enquiry were employed.
From the late fifteenth century much of its jurisdiction was exercised through the Council in Star Chamber, sitting most usually under the presidency of the Chancellor, and the Court of Requests. Within the Council itself judicial and administrative functions became differentiated in the course of the sixteenth century, a result of the development of the Privy Council, from which the Court of Star Chamber became institutionally distinct. Conciliar jurisdiction in certain parts of England and Wales was exercised through specialised councils such as the Councils of the North, Wales and the Marches, and the West. The non-equitable jurisdiction of the Council was increasingly committed to the Court of Star Chamber which, together with the Court of High Commission, also dealt with ecclesiastical cases.
The conciliar courts were abolished in 1641 or allowed to lapse shortly afterwards, though under James II there was a short lived attempt to revive the High Commission. The Council thus lost much of its judicial authority, retaining only the hearing of appeals from colonies and dependancies of the crown, the conduct of examinations in treason and political cases, appeals from the Prize Courts and an ultimate appellate jurisdiction from the Court of Delegates in admiralty and ecclesiastical cases under petitions for commissions of review. In 1832 on the abolition of the Court of Delegates the powers of that court passed to the king in Council, and in the following year were vested in the Privy Council's new Judicial Committee, along with the hearing of appeals from overseas.
The political authority of the Privy Council, at its height under the later Tudors and the early Stuarts, began to decline under Charles II. Political power passed to the secretaries of state and other ministers dominating boards such as the Treasury and the Admiralty who came to depend during the eighteenth century upon their command of a majority in Parliament. Membership of the Privy Council became either a political formality or a public honour. Now Cabinet ministers are automatically appointed to the Privy Council, as are certain members of the royal family, the archbishops of Canterbury and York, the bishop of London, the Lord Chief Justice and the lords justices of Appeal. Other members are appointed on the recommendation of the Prime Minister in recognition of public or political service in the United Kingdom or other Commonwealth countries. Aliens, unless naturalised, are ineligible. The full Council, consisting of about three hundred persons is rarely summoned and meetings convened by the Clerk of the Council normally consist of only four or five members.
The legislative role of the Privy Council now consists of making orders in Council and issuing royal proclamations. Orders in Council are of two kinds: prerogative, such as those relating to the constitutions or currency of overseas territories; and statutory, made under the authority of an Act of Parliament. They are to be distinguished from orders of Council which are made by the lords of the Privy Council alone, usually acting as overseers of the medical, dental and pharmaceutical professions. Royal proclamations are issued on the advice of the Privy Council when it is desired to give wide publicity to the action of the sovereign in Council, as for the purpose of dissolving, proroguing or summoning Parliament.
The administrative work of the Privy Council has diminished gradually with the transfer of fields of responsibility to committees of the Council or to other government departments. Such work as remains is of a residual and multifarious character. The Council itself still authorises the issue of charters and letters patent under the great sealand appoints and swears in many senior appointees. The larger part of its administrative work is now discharged by the Privy Council Office or committees.