He was killed, along with his wife Cecily, Lady Gibson by the Provisional Irish Republican Army (IRA).

[2] Lord Justice Gibson and his wife were killed by a remote-controlled car bomb as they drove over the Irish border back into Northern Ireland on 25 April 1987 after a holiday in the USA.

As the judge's car reached Drumad, the townland on the County Louth side of the border, he stopped to shake hands with the Garda Síochána security escort who had completed their part of the assignment.

[1][3] The explosion also injured Ireland national rugby union team players Nigel Carr, David Irwin and Philip Rainey who were in a car on the same road.

The later Smithwick Tribunal found that Cory had been 'mistaken' in questioning the reliability of intelligence that a member of the Garda had helped the IRA in the Gibsons' murders, and in May 2014, former Northern Ireland First Minister Lord Trimble called for an inquiry into whether there was collusion.