McBirney studied law at Trinity College Dublin and became a barrister in Belfast, before being called to the bar at Gray's Inn.
[2][3] McBirney stood for the NILP in Belfast Willowfield at the 1965 Northern Ireland general election, taking 35.1% of the vote.
He was made a Queen's Counsel, was appointed a resident magistrate,[2] and served as Senior Crown Prosecutor for Belfast.
He worked as a lawyer for the defence on civil rights cases, including one involving the Derry Citizens' Action Committee, in which he defended, among others, Eamonn McCann.
On the same day another judge, Rory Conaghan, was shot dead by the IRA outside his home at Beechlands off the Malone Road, Belfast.
[3] Poet Michael Longley later revealed that he had written the poem A Civil Servant in McBirney's honour.