Expulsion of a member from the House of Commons is the ultimate sanction.
It cannot be challenged and is an outstanding example of the House's power to control its own proceedings.
MPs are usually expelled for being unfit for office although they can also be expelled for a serious offence against the House.
No corresponding sanction exists in the Lords to expel a Peer from the House.
If a MP is to be expelled, the Speaker will bring a motion that the named member should be expelled.
In cases where the MP may be able to make explanation he or she can come before the House to make a statement.
But in cases where no explanation would mitigate the ruling, the MP will be expelled in his or her absence.
A by-election must then be held to find a replacement MP.
20th century expulsions:
• 16 December 1954
Peter Baker (Con) South Norfolk, was expelled after he was sentenced to seven years imprisonment for forgery;
• 30 October 1947
Garry Hallighan (Lab) Gravesend, was expelled for lying to a committee and gross contempt for the House. This followed the publication of an article in the World's press news accusing members of insobriety and of taking fees or bribes for the supply of information;
• August 1922
Horatio Bottomley, (Ind) South Hackney, was expelled in August 1922 after he was convicted of fraudulence and conversion of property. He was sentenced to seven years imprisonment.