O'Regan was educated at University College Cork and the King's Inns.
[6] She has heard cases involving property law,[7] personal injuries,[8] judicial review,[9] insolvency,[10] extradition,[11] injunctions,[12] and defamation.
[13] She has presided over a defamation dispute involving Declan Ganley, Denis O'Brien and Red Flag Consulting.
[14] Her experience of other high-profile actions includes the bankruptcy of Seán Dunne,[15] contempt of court by the Irish Independent,[16] and an action against Rihanna, who was accused of uttering malicious falsehoods.
[17] She made a reference to the European Court of Justice in 2019 regarding an environmental law case.