Burns attended Trinity College Dublin where he obtained a bachelor's degree in legal science in 1984 and a Master of Letters in law in 1987.
[2] His practice was predominantly focused on criminal law, appearing for both accused persons and the Director of Public Prosecutions.
[14][15][16] In 2007, he was counsel for the Garda Síochána in a case for damages taken by Frank McBrearty Snr and appeared for solicitor Michael Lynn in preliminary hearings.
[17][18] Burns has also represented the wife of John Gilligan in civil proceedings and, in defamation actions against media organisations, Declan Ganley, Paddy McKillen and Denis O'Brien.
[26][27] In October 2020, he refused to order the extradition of Ian Bailey to France for trial arising from the death of Sophie Toscan du Plantier.