Parliamentary Privilege in the Middle Ages
Among the earliest of the privileges claimed by the Lords and Commons in Parliament was protection from arrest and imprisonment. A form of this protection had been enjoyed by those attending the councils of the Anglo-Saxon kings, but it did not find its way into formal statute law after the Norman Conquest. Initially, the protection pertained to the king rather than to Parliament: it was designed to ensure that the king’s interests were not damaged by the arrest of those who came to advise him, and a similar form of protection was extended to those who came to sue in the royal law courts at Westminster.
By the reign of Edward I the privilege was extended to the servants of peers attending Parliament, as well as magnates themselves, while the earliest known example of a Member of the Commons claiming immunity dates from 1340. From the early fifteenth century t