According to Erskine May, which sets out rules governing Parliament, The Parliamentary Witnesses Oaths Act 1871 “empowers the House of Commons and its committees to administer oaths to witnesses, and attaches to false evidence the penalties of perjury”.
It says: “Where evidence is not given upon oath, the giving of false evidence is punishable as a contempt. It is not usual, however, for select committees to examine witnesses upon oath, except upon inquiries of a judicial or other special character.”
Paul Farrelly MP,a Labour member of the committee, told The Daily Telegraph: “We will take advice on Tuesday morning from clerks whether we will require them on this occasion to take testimony under oath.
“That power is available to the committee but it is rarely used and what is appropriate on this occasion given the misleading evidence to this inquiry from News International.”