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Source: Custom

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  • in addition to legislation and judicial decisions, other legal sources of the constitution include Royal Prerogative and Parliamentary law and customs

Royal Prerogative

  • Government power is derived from legislation passed by Parliament
  • Ministers often be authorised to take decisions by an Act of Parliament (statutory powers) but also prerogative powers exist
  • Dicey: definition the royal prerogative is .. the residue of discretionary or arbitrary authority which, at any given time is legally left in the hands of the Crown... Every act which the government can lawfully do without the authority of an Act of Parliament is done in virtue of this prerogative... (An Introduction to the Study of the Law of the Constitution (1885))

Modern Meaning

  • powers were part of the common law - bridge between absolute monarchy and parliamentary supremacy
  • some powers remain but are effectively exercised by the Government not the monarch
  • domestic: summoning of Parliament, appointment and dismissal of the Prime Minister, Royal Assent to Bills, deployment of armed forces within UK (defence of the realm) and granting of honours
  • foreign affairs: declaration of war and deployment of troops overseas, concluding of international treaties and recognition of foreign states

Parliamentary Customs

  • broad and uncertain
  • based on the common law privilege of each institution to regulate its own proceedings
  • relate to freedom of speech in Parliament and legal immunities
  • concept can be found in Bill of Rights 1689, which prohibits interference with Parliament by outside bodies

    Bill of Rights 1689

    • Article 9: .. freedom of speech and debates or proceedings in Parliament ought not to be impeached or questioned in any court or place out of Parliament...
  • Joint Committee on Parliamentary Privilege: .. The modern interpretation is now well established: that article 9 and the constitutional principle it encapsulates protect members of both Houses from being subjected to any penalty, civil or criminal, in any court or tribunal for what they have said in the course of proceedings in Parliament... (1999)


  • authority found in Erskine May's Parliamentary Practice, edited by Clerk of House of Commons
  • reference book is secondary not primary source of law
  • four primary sources: practice, Standing Orders, Speaker's rulings and statute


  • precedent means established procedures will be followed unless explicitly altered in statute
  • can be found through evidence from official Journals of the House
  • rule that each Bill is read three times in each House is followed as a matter of precedent
  • Standing Orders

  • written rules relating to the conduct of Parliamentary business
  • regulate MPs behavoiur, how Bills are processed and debates organised
  • order is passed by a majority in a single vote in House of Commons
  • some are temporary and last until the end of a session
  • around 150 relating to parliamentary business and public Bills and about 250 relating to private business
  • Speaker’s Rulings

  • rulings made by Speaker of the House of Commons can be a precedent for the future
  • Speaker has been elected by the House to provide guidance and enforce procedures
  • Statute

  • statute can relate to Parliamentary procedures
  • Statutory Instruments Act 1946 sets out process for delegated legislation
  • such Acts should be enforced by Parliament itself rather than courts


  • question of enforcing Parliamentary law and custom is complex
  • raises issues both inside and outside of Parliament

    House of Commons

  • Speaker primarily responsible for enforcing law and custom of Parliament
  • role: directing an MP to withdraw remarks if they are inappropriate, naming which means putting forward MPs for suspension and suspending the sitting of the House due to serious disorder
  • Sergeant at Arms directs police on duty in the House and acts on the authority of the House outside the House
  • House of Lords

  • less formal enforcement procedure
  • Lord Speaker has no powers to enforce order
  • Peers expected to observe the rules
  • Courts

  • Parliamentary law and custom is distinguished from other sources of UK constitution as it is not enforced by courts
  • statute prevails over Parliamentary custom however, relationship between common law and Parliamentary custom lacks clarity
  • courts can recognise the existence but not enforce, as that is a matter for Parliament
    Bowles v. Bank of England [1913]
    • found that resolutions have no legal force outside Parliament itself
    • with exception of budgetary resolutions
    Stockdale v. Hansard (1839)
    • held each House was sole judge of its own privileges
    • resolution of the House declaratory of its own privileges could not be questioned in any court

Authoritative Works

  • works by leading academic commentators can be taken into account by courts when determining constitutional points
  • not binding authority but can be persuasive
  • for example Dicey's Introduction to the Study of the Law of the Constitution or Erskine May's Parliamentary Practice
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