He obtained a John F. Kennedy memorial scholarship to study for an LLM, which he earned in 1982 from the University of Pennsylvania Law School.

[10] He was involved with the Progressive Democrats and in 1988 wrote the party's proposed new Constitution of Ireland with Michael McDowell.

[15] He acted for the Attorney General of Ireland in references made by President Mary Robinson under Article 26 of the Constitution of Ireland to the Supreme Court regarding the Information (Termination of Pregnancies) Bill 1995 and the Employment Equality Bill of 1997.

[16][17] He appeared again for the Attorney General (with Dermot Gleeson and Paul Gallagher) in another reference made by President Mary McAleese regarding the Health (Amendment) (No.

[22] He has also written a text on political violence and a book where he chronicled the origins of the Constitution of Ireland.

[32][33] In 2008, he acted for Colm Murphy and Seamus Daly in the Supreme Court who were contesting an action taken by families of victims of the Omagh bombing when they were refused access to books of evidence.

[37][38] He acted for the Committee on Members’ Interests of Seanad Éireann in action taken by Ivor Callely.

He was also a member of the Competition Authority's Advisory Panel and the Committee on Court Practice and Procedure.

Soon after his appointment, he held an emergency hearing in his home regarding a blood transfusion for a sick baby.

[15] In May 2018, he was nominated by the Government of Ireland for appointment as the Advocate General to the European Court of Justice.