Mr Spierin maintained a practice at the Bar from 1985, calling to the Inner Bar in 1999 and retiring in July 2022.

He was previously a member of staff of the High Court Probate Office.

For many years, he was the lecturer in civil practice and procedure at the Honorable Society of King’s Inns.

Mr Spierin was the author of The Succession Act and Related Legislation: A Commentary, which won the Dublin Solicitors Bar Association (DSBA) Book of the Year in 2018, and of Wills: Irish Precedents and Drafting, also nominated for Practical Book of the Year by the DSBA.