Born in the Bronx and raised in Westchester County, John graduated from Hendrick Hudson High School in Montrose, NY in 1988. John received his Bachelor of Arts degree in English Literature from New York University in 1992 and his Juris Doctorate, summa cum laude, from New York Law School in 2001. After graduating law school, John lived in Manhattan and Los Angeles working for large national law firms representing Fortune 500 companies in a variety of civil litigation practice areas. John moved to Sag Harbor in 2012 to be closer to his mother, Dolores Leonard. He met his husband, Gene, in Bridgehampton in 2013 and they were married in 2018.

John started his private law practice on the East End in 2016 with the opening of his first law office in Sag Harbor that year. John's practice focuses on complex civil litigation, matrimonial and family law, estate planning and real estate. In 2017, John moved his law practice to Hampton Bays and, in 2022, John and Gene moved their residence to Hampton Bays from Sag Harbor. 

John is an ardent community advocate. He has taken on countless cases pro bono for victims and survivors of domestic violence under the umbrella of such not-for-profit charities as the Retreat in East Hampton and Nassau/Suffolk Law Services in Islandia, as well as privately through his law firm. John served on the Sag Harbor Chamber of Commerce for many years and has volunteered on the Town's drug treatment court - the East End Regional Intervention Court - since 2017 helping criminal defendants obtain much needed substance abuse treatment and long lasting sobriey. John was appointed to the Town of Southampton Architectural Review Board in 2021 and then to the Town's Zoning Board of Appeals in 2022; he has served on the Zoning Board ever since. In 2024, John co-founded the Hampton Bays Alliance, a not-for-profit civic organization providing educational programming to the public on such important issues as development in the Town, affordable housing, and the revitalization of the Hampton Bays downtown district. Through the Alliance, John embraces the core values of civility, inclusivity and progress, and endeavors to defuse the needless politicization of our local government by encouraging consensus through civil public discourse and active public engagement in our civic institutions.

In his spare time, John is an avid skier, reader, theatergoer and actor. John has been active in community theater since moving to the East End, having been cast over the years in a variety of theatrical productions at the Southampton Cultural Center in Southampton, LTV in East Hampton, and the Bay Street Theater in Sag Harbor. John is also a huge animal lover and has had dogs as companions consistently throughout his life. Having lost two senior pups recently to old age, he and Gene have been blessed with a tiny, black and white Chihuahua named Timmy who they rescued in 2023 as a puppy. Timmy is a regular fixture in John's law office as he travels to work with John every day.