There are two types of House of Commons Select Committee – departmental and non-departmental.
Departmental Select Committees are charged with examining the spending, administration and policy of their specific department and its related public bodies. They may take evidence from witnesses and require the submission of documents, and they may set up sub-committees to carry out specific inquiries. They report to the main House of Commons from time to time on topics of their choosing and, while the Government is required to respond within two months, there is no requirement that their reports be debated by MPs.
Non-departmental select committees, include the Public Accounts Committee (known as PAC as well as the Select Committee on Public Accounts), the Public Administration Select Committee (known as PASC),and the Committee on Standards and Privileges. They exist to consider issues within their specific, cross-departmental terms of reference.
The Committee of Selection nominates members for each Select Committee after discussion by the Usual Channels (party whips offices). A motion is then put to the House, which normally approves the membership without debate or vote, although either may take place.
New Select Committee memberships are appointed after each General Election but these may be altered at any time thereafter. The normal membership of a Select Committees is around 11 MPs with the party split within a Select Committee typically mirroring that found within the House of Commons as a whole.
Each Select Committee has one MP, typically a more experienced parliamentarian, who acts as their particular Chairman or Chairwoman.
The Liaison Committee is a committee which made up of all the Chairs of the various select committees. Its most prominent role is the questioning the Prime Minister once every six months.
The Modernisation Committee makes recommendations on changes to the practices of the House of Commons. Its membership includes a government Minister, the Leader of the House of Commons.
There are other ‘domestic’ committees, which deal with the running of the House. These include the Accommodation and Works and Catering Committees.
Normally, a committee will issue an informal request to a witness to attend, and most witnesses will do so willingly. But if a witness proves unwilling, a committee can resort to using its powers and formally summon them.
House of Commons Select Committees typically put in a request for potential witnesses to attend, give evidence and answer their Members questions. If that request is not forthcoming, the Committee can potentially issue a summons for people to attend. This means that a Select Committee can compel witnesses within the UK (other than the Crown and members of the Commons and Lords) to attend and answer questions.
Having been summoned by the Culture, Media and Sport Select Committee, Rupert Murdoch finally agreed attend to answer questions about phone hacking in the media.