[8][9] She was a legal advisor to an inquiry into Deposit interest retention tax conducted by the Public Accounts Committee, along with future judicial colleagues Frank Clarke and Paul Gilligan.
As a junior counsel, she represented the plaintiff in Cahill v. Sutton in 1980 in the Supreme Court with seniors Niall McCarthy and James O'Driscoll.
[12] She appeared with Peter Kelly to argue on behalf the right of the unborn in a reference made by President Mary Robinson under Article 26 of the Constitution to the Supreme Court in 1995 regarding the Information (Termination of Pregnancies) Bill 1995.
[19] She was appointed to chair a statutory tribunal to conduct hearings and deal with cases related to the CervicalCheck cancer scandal in 2019.
[26] Irvine was appointed by Chief Justice Frank Clarke in 2019 to chair the Personal Injuries Guidelines Committee of the Judicial Council.
[18] The purpose of the committee is to review the levels of compensation issues in court cases arising out of personal injuries.
[27] Minister of State at the Department of Finance Michael W. D'Arcy wrote a letter to congratulate Irvine on her appointment and outlined his views that personal injuries awards in Ireland should be "recalibrated".
[28] Following a cabinet meeting on 12 June 2020, it was announced that she would be nominated to succeed Peter Kelly as President of the High Court.
[29] A three-person panel consisting of the Chief Justice Frank Clarke (later substituted by George Birmingham[30]), the Attorney General Séamus Woulfe and a management consultant Jane Williams reviewed applications for the position, before making recommendations to cabinet.
She issued guidelines for lawyers to negotiate personal injury cases outside of court due to the backlog formed by delays in hearings.