McCloskey was called to the bar in 1979, and made a Queen's Counsel (QC) in 1999.[1] He was appointed a High Court Judge in September 2008.[2] As is customary for High Court judges, he was appointed a Knight Bachelor and therefore granted the title sir: he was knighted by Queen Elizabeth II during a ceremony at Buckingham Palace on 3 March 2009.[3] He served as chair of the Northern Ireland Law Commission from 2009 to 2012.[4][5][6] He was appointed a Lords Justice of Appeal of Northern Ireland on 5 September 2019,[7] and subsequently appointed to the Privy Council.[1]