Known for his speciality in constitutional law, and frequent appearances on behalf of the State while a barrister, the graduate of UCD Sutherland School of Law rose to the highest judicial office in Ireland when he was appointed chief justice in 2021 after more than a decade on the Supreme Court.

His distinguished career has established him as a legal thinker of national and international standing, and one of the foremost jurists of his generation.

Made a bencher of the King’s Inns in 2009, the following year the Belfast native was appointed directly to the Supreme Court from the bar — a rare and unusual honour.

Beyond the courtroom, he has published widely on constitutional and legal history, served on the Law Reform Commission, and held roles with Our Lady’s Hospice and the Irish Legal History Society. 

Throughout his career, Mr Justice O’Donnell has maintained strong ties with UCD, delivering lectures, contributing to research, and supporting student initiatives such as the Law Review, the Legal Service and the Law Society.

His father, the late Turlough O’Donnell, served as a High Court judge in Northern Ireland during the Troubles, presiding over some of the most high-profile trials of the era including that of the Shankill Butchers.

Dr Niamh Howlin, associate professor in UCD Sutherland School of Law, read the official citation for Mr Justice O’Donnell.