Parliamentary Privilege

Erskine May, Parliament's own authoritative guide to procedure and privilege, defines parliamentary privilege as 'the sum of certain rights enjoyed by each House collectively as a constituent part of the High Court of Parliament and by Members of each House individually, without which they could not discharge their functions, and which exceed those possessed by other bodies or individuals'. Some of these privileges rest on the law and custom of Parliament, while others are defined by statute. The MPs' Guide to Procedure summarises the core purpose more simply: privilege 'gives the two Houses, their committees and members, the protection from outside interference or legal action necessary to perform their roles', and its 'two main elements are freedom of speech and the right of both Houses to regulate their own affairs'.

The most significant statutory privilege is freedom of speech under Article IX of the Bill of Rights 1689. As Erskine May explains, this provision 'lays on courts an obligation not to "impeach or question" proceedings in Parliament', and 'the prohibition is statute law' which, absent amending legislation, 'cannot be waived by either House'. Because Article IX is statutory rather than merely a matter of parliamentary custom, the courts have treated it as unusually robust: Erskine May records that the Bill of Rights 'has been judicially recognised as a constitutional statute and as such not amenable to implied repeal'. Where a privilege is disregarded or attacked, this is called a breach of privilege, and each House also claims the separate power to punish contempts — actions that obstruct it in performing its functions or offend its authority or dignity.