Kiernan was appointed by Suffolk County Executive Edward Romaine after receiving unanimous approval from the Suffolk County Legislature.
He fills a vacancy in the Third Judicial District created when Judge Bronwyn Black-Kelly was elected to the New York State Supreme Court in 2025.
The ceremony drew several prominent members of the legal community, including District Administrative Judge Andrew Crecca, former New York State Chief Administrative Judge A. Gail Prudenti, and Suffolk County Surrogate Vincent Messina.
Suffolk County Clerk Vincent Puleo administered the oath of office.A resident of Cold Spring Harbor, Kiernan brings extensive experience from both the public and private sectors.
He served twice as Suffolk County Public Administrator, from 1998 to 2002 and again from 2018 to 2023. His career also includes roles as Special Counsel to the Chief Administrative Judge of New York and to the Executive Director of the Permanent Judicial Commission on Justice for Children.
Kiernan has held several positions within the court system, including Deputy Clerk and Clerk of the Court for the Appellate Division, Second Judicial Department. Earlier roles include Principal Law Clerk to the Suffolk County Surrogate, Assistant Town Attorney for the Town of Southold, and Special Assistant District Attorney in Suffolk County.
In private practice, he worked with multiple law firms and is also a certified arbitrator and mediator. He has taught at Hofstra University and remained active in bar associations.
“I look forward to serving the people of Suffolk County,” Kiernan said, pledging to uphold the law with integrity.
Judge Kiernan will be assigned to a civil part in the Third District Court in Huntington.