The Queen’s Privy Council for Canada was established by the British North America Act, 1867 (later renamed the Constitution Act, 1867), which provides in Section 11:
There shall be a Council to aid and advise in the Government of Canada, to be styled the Queen's Privy Council for Canada; and the Persons who are to be Members of that Council shall be from Time to Time chosen and summoned by the Governor General and sworn in as Privy Councillors, and Members thereof may be from Time to Time removed by the Governor General.
On the advice of the Prime Minister, the Governor General appoints new ministers to the Queen’s Privy Council before they are sworn in as ministers. The Prime Minister of the day may choose to recommend the appointment of other persons of distinction as a special form of honour.
The Queen’s Privy Council for Canada thus includes not only members of the present ministry but also former ministers and other distinguished persons.
As Professor Robert MacGregor Dawson said, "The Privy Council would...if active, be a large and politically cumbersome body...with members continually at cross-purposes with one another. It has saved itself from this embarrassment by the very simple and effective device of holding almost no meetings of the whole council." 1
1. Norman Ward, Dawson’s The Government of Canada. 6th ed. (Toronto: University of Toronto Press, 1987), p.198.