Desmond Marrinan was called to the Bar of Northern Ireland in 1972 and later to the Irish Bar. He specialised in EC law, criminal law and professional negligence litigation until appointment as a County Court judge in 2003.
He lectured in public law at the Queen’s University of Belfast from 1971-1978 and latterly was an external examiner for the Institute of Professional Legal Studies at Queens. He was formerly the Vice-Chair of the Law Reform Advisory Committee.
He served as a County Court judge until 2018 dealing mostly with criminal trials in the Crown Court. He was the Recorder of Londonderry from 2008-2011 and continues to sit as a Deputy County Court judge and as a Parole Commissioner.