MPs on the Commons public accounts committee flexed a rarely-used muscle on Monday, when they compelled the the top lawyer for HM Revenue and Customs to swear an oath on a Bible before answering their questions.
Anthony Inglese, general counsel and solicitor, HMRC, was appearing before the public accounts committee on Monday to answer questions about tax deals struck with Goldman Sachs and Vodafone.
Critics have slammed the deal struck by Dave Hartnett, the permanent Secretary for Tax, for letting the two companies get away with not paying £10m and £6bn in tax respectively.
The session was highly combative from the offset, with committee members becoming increasingly irate with Inglese's refusal to answer questions on the basis of his duty to keep confidences as a lawyer.
But the MPs said his duty as a civil servant to be held accountable by Parliament overruled any other considerations.
Having finally lost patience with Inglese, the committee's chair, Labour MP Margaret Hodge, told him: We are taking an unusual step. It is a power we have. From here onwards were going to examine you on oath."
Inglese was then handed a Bible by the clerk of the committee, who said he had the option of either swearing an oath or taking the non-religious affirmation option.
His plea to have "a minutes time out" to digest what was happening to him was rejected.
Tory committee member Richard Bacon snapped back: "No. I don't see why you should have a minutes time out at all."
"This committee has the power to make witnesses give evidence under oath and we're doing so, the reason is we haven't been able to get answers otherwise, so I think we should just get on with it."
Inglese then read out loud: "I swear by all mighty god the evidence I give before this committee shall be the truth, the whole truth and nothing but the whole truth, so help me god."
The decision to make Inglese give evidence under oath is, as hodge indicated, highly unusual. Indeed despite the high media profile and gravity of the allegations, the Commons culture committee chose not to make Rupert and James Murdoch give evidence under oath when they appeared before MPs over the phone hacking scandal in July.
Commons committees are often dismissed as having less teeth than their counterparts in other countries including those of the United States Congress.
But Erskine May, the parliamentary rule book, does give them the power to compel witnesses to take an oath.
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”.
A power not lost on Hodge, who told Inglese: "I'm no lawyer, but having taken the oath you don't want to give answers that are incorrect, as you might find yourself with the accusation of having committed perjury."
Hodge's decision could lead other committee chairs to consider whether to force their witnesses to give evidence under oath.