Hugh Kennedy, the new Chief Justice of Ireland, recommended Fitzgibbon as a judge of the Supreme Court of Ireland simply on account of his legal ability,[5] despite their serious differences on political issues, which Hogan refers to as a clash between Kennedy's "enthusiastic nationalism" and Fitzgibbon's "pessimistic scepticism".
Although Fitzgibbon was a Protestant Unionist, his friends insisted that he was by no means opposed to the new regime[7] and indeed if he had been, he would hardly have accepted high office in it.
However, he seems to have become deeply disillusioned with the increasingly Roman Catholic Irish Free State, and by 1929, he and Chief Justice Kennedy are said to have regarded each other with deep suspicion.
Despite his obvious unhappiness in his professional life, he remained on the Supreme Court of Ireland until he reached retirement age in 1938; Chief Justice Kennedy believed that his somewhat unsatisfactory pension arrangements made Fitzgibbon cling to an office he had come to despise.
Hogan points out that in this regard at least Fitzgibbon had good reason to be bitter with his treatment by the Government, because he was required on age grounds to retire 9 months before he qualified for the full amount, he seems to have received a pension equivalent to only 42% of his salary.