MPs questioning the most senior solicitor at HM Revenue and Customs have taken the very rare move of forcing him to give evidence under oath.
Committee chair Margaret Hodge halted the proceedings on 7 November 2011 and ordered Anthony Inglese to stop and take an oath after 35 minutes of questioning.
He had been accused of evasive behaviour after repeatedly telling the committee he was unable to answer numerous questions about the disclosure of information.
The session was part of an inquiry by the committee into an agreement between HMRC and Vodafone. The mobile giant agreed to pay £1.25bn in arrears.
Mr Ingelse insisted he was unable to reveal some information because he claimed he was protected by legal privilege.
A separate deal with Goldman Sachs is believed to have saved the company £10m of tax.
HMRC's top tax official David Hartnett appeared before the committee, despite having given evidence on a previous occasion, after MPs raised concerns over the quality of his evidence.
He has told the committee that he did not deal with Goldman Sachs affairs "in the normal sense", but confirmed that there were issues of "oversight" by HMRC that he was keen to address.
The committee also heard from cabinet secretary Gus O'Donnell who announced that two new tax commissioners would be appointed.
The General Commissioners of Income Tax is a tribunal which hears appeals against decisions made by HMRC on a variety of different tax related matters.