The right of MPs or Lords to make certain statements within Parliament without being subject to outside influence, including law. Parliamentary privilege grants certain legal immunities for Members of both Houses to allow them to perform their duties without interference from outside of the House. Parliamentary privilege includes freedom of speech and the right of both Houses to regulate their own affairs.The privileges are only codified a work of authority in Erskine May: Parliamentary Practice

In recent years the doctrine of parliamentary privilege has made headlines in relation to several cases relating to super-injunctions such as RJW & SJW v The Guardian newspaper & Person or Persons Unknown ('Trafigura') and CTB v News Group Newspapers.

The Liberal Democrat politician John Hemming used parliamentary privilege to reveal the litigant involved in the case CTB v News Group Newspapers.