
In theWestminster system used in manyCommonwealth realms, theKing-in-Parliament (Queen-in-Parliament during the reign of a queen) is aconstitutional law concept that refers to the components ofparliament – the sovereign (orvice-regal representative) and the legislative houses – acting together to enact legislation.[1][2][3][4][5]
Parliamentary sovereignty is a concept in the constitutional law of Westminster systems that holds that parliament has absolutesovereignty and is supreme over all other government institutions. The King-in-Parliament as a composite body (that is, parliament) exercises this legislative authority.
Bills passed by the houses are sent to the sovereign or their representative (such as thegovernor-general,lieutenant-governor, orgovernor), forroyal assent in order to enact them into law asacts of Parliament. An Act may also provide forsecondary legislation, which can be made by executive officers of the Crown such as through anorder in council.[6][7]
The concept ofthe Crown as a part of parliament is related to the idea of thefusion of powers, meaning that theexecutive branch andlegislative branch of government are fused together. This is a key concept of theWestminster system of government, developed in England and used in countries in theCommonwealth of Nations and beyond. It is in contradistinction to the idea of theseparation of powers.
In Commonwealth realms that arefederations, the concept of the King in parliament applies within that specific parliament only, as each sub-national parliament is considered separate and distinct from each other and from the federal parliaments (such asAustralian states or theCanadian provinces).

According to constitutional scholarA.V. Dicey, "Parliament means, in the mouth of a lawyer (though the word has often a different sense in ordinary conversation), the King, the House of Lords, and the House of Commons; these three bodies acting together may be aptly described as the 'King in Parliament,' and constitute Parliament."[2] Legal philosopherH. L. A. Hart wrote that the Queen-in-Parliament is “considered as a single continuing legislative entity”.[8]
Constitutional scholarIvor Jennings described the Queen-in-Parliament as "a purely formal body consisting of the Queen sitting on her Throne with the Lords of Parliament sitting before her and the Commons standing at the Bar."[1] This formal gathering was historically the only process by which legislation could be enacted. TheRoyal Assent by Commission Act 1541 allowedLords Commissioners to stand in for the monarch, and theRoyal Assent Act 1967 allowed legislation to be enacted by pronunciation, without a physical gathering. The assembling of the King, Lords, and Commons as the King-in-Parliament is now "notional rather than real",[9] only occurring ceremonially at the annualState Opening of Parliament.[1][10]
The composition of the King-in-Parliament is reflected in theenacting clause of acts of the British Parliament with: "Be it enacted by the King's most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the authority of the same, as follows...".

InEngland, by the mid-16th century, it was established that the "King in Parliament" held supreme legislative authority.[12] However, this phrase was subject to two competing theories of interpretation.[12][13][14] The Royalist view interpreted the phrase as "King, in Parliament"; that is, the King acting with the consent of the Lords and Commons, but ultimately exercising his own sovereign authority.[13] The Parliamentarian view was that legislative authority was exercised by the "King-in-Parliament”, a composite institution of the King, Lords, and Commons acting together.[13]
As described byJeffrey Goldsworthy, "The question that divided them was whether [the] final, unchallengeable decision-maker was the king alone, or the King, Lords, and Commons in parliament."[12] The dispute had implications for the ability of Parliament to limit the monarch’s powers, or "the supremacy of the King in Parliament over the King out of Parliament."[15] The clash between the Royalist and Parliamentarian views continued through the 16th century and much of the 17th, and was a factor in theEnglish Civil War (1642-1651) and theexecution of Charles I (1649).[13][16]
The Parliamentarian position ultimately prevailed with theGlorious Revolution (1688–89) and subsequent passing of theBill of Rights 1689, which significantly limited the day-to-day powers of the monarch, including removing prerogative powers to unilaterally suspend or dispense with statutes.[17]

The concept of the King-in-Parliament holding supreme legislative authority is a core tenet of theConstitution of the United Kingdom and has application in the Westminster system more generally.[18] As a concept, legislative authority being exercised by the King-in-Parliament is compatible with different distributions of power among its three components.[12][19] This allowed for increasing limitations on the monarch’s direct and unilateral influence within Parliament over the 18th and 19th centuries.[20] The influence of the House of Lords has also been significantly limited, most notably by theParliament Acts 1911 and 1949, which allow money bills to be passed against the wishes of the House of Lords. Such legislation can still be understood in a constitutional sense to be an act of the King-in-Parliament, that is by the King, Lords, and Commons acting jointly as a single body known as parliament.[21]
In order to act as the King-in-Parliament, the individual components must act according to their established rules and procedures. The individuals involved must be "constituted as a public institution qua Parliament (on the basis of some rules and under certain circumstances)" in order to "[enjoy] the power to legislate as 'the [King] in Parliament' i.e., the ultimate legislature."[22] This creates a potential paradox when determining Parliament’s ability to modify its own rules or composition.[22]

Section 17 of Canada'sConstitution Act, 1867 establishes theParliament of Canada as the legislative authority for the country, defining it as consisting of "the Queen [or King], an Upper House styled the Senate, and the House of Commons." The Parliament of Canada may be referred to as the King-in-Parliament,[4] and its three-part composition is based on "the British model of legislative sovereignty vesting in the [King]-in-Parliament".[23] Canadian acts of Parliament use the enacting clause: "Now, therefore, His Majesty, by and with the advice and consent of the Senate and House of Commons of Canada, enacts as follows..."
Canada's provincial legislatures are constitutionally defined as consisting of the province'slieutenant governor (as the representative of the King) and a popularly elected legislative assembly. The concept of King-in-Parliament also applies to these sub-national legislatures.[4]
Legal scholarPaul McHugh describes Canada as having "a crisis of constitutional identity" in the later 20th century, finding "the oldWhig narrative of an absolute sovereign self (the Crown in Parliament)" to be inadequate. The Canadian response was to "not seek to refurbish a historical order so much as to fundamentally reorder it by adopting theCharter of Rights and Freedoms limiting the power of government, the Crown in Parliament (federal and provincial) included."[18]
TheNew Zealand Parliament consists of themonarch and theNew Zealand House of Representatives.