Originally from Dublin, Ireland, Niall MacGiollabhuí received his law degree from the University of Dublin, Trinity College, and practiced in Ireland as a solicitor for a number of years.  In 2006, he moved to New York and joined the Law Office of Michael G. Dowd, the renowned criminal defense attorney.  In 2016, he established his own firm, The Law Office of Niall MacGiollabhuí, focused  on criminal defense work and civil litigation.  His practice spans state and federal courts in New York, at both trial court and appellate levels. 

Niall has successfully defended people from all walks of life accused of all manner of crimes, from Barbara Sheehan, acquitted of murdering her husband after suffering decades of horrific domestic abuse, to Seán Garland, formerly a leading figure within the Official IRA, whose extradition from Ireland was unsuccessfully sought by US federal authorities based on allegations that he masterminded a counterfeit currency ring in Europe with “superdollars” supplied by the North Korean government, to Sam Kellner, a Hasidic Jewish father who was falsely accused and prosecuted for extortion and subornation of perjury when he exposed a serial abuser of children from a powerful family within his community, who molested his son, by helping other victims to come forward and report their abuse. 

Many of his cases have been widely reported-upon, and he was the subject of a documentary in 2014, entitled “In Niall We Trust,” shown on TG4, the national Irish-language television station in Ireland.  He has been recognized as a Rising Star in the area of Criminal Defense each year since 2013 by Super Lawyers, an award reserved for the top 2.5% of lawyers under 40.  He is one of a small handful of lawyers in New York to appear in that category for each of these years.

In his criminal defense practice, Niall has handled every kind of case, including first and second degree murder.  He also represents victims of crimes in civil proceedings, and victims of civil rights violations, as well as providing representation in a diverse range of other civil litigation matters.

He is active in a number of Irish-American organizations, serving as a director of the Irish American Bar Association of New York, and as Vice-President of the Brehon Law Society.