After his enforced retirement in 1924, he practised at the English bar until 1929, when he returned to Ireland and was readmitted to practice as a solicitor, a controversial move necessitating a leading judgment on the standard of professional conduct to be expected of a former judge.
The Chief Justice, Hugh Kennedy, made clear his disapproval of this conduct, required a further detailed affidavit and asked for the attendance of the Attorney General.
He noted that, although some senior English judges like Francis Pemberton had returned to practice at the bar, none had done so since the Act of Settlement 1701, which in his view reflected the understanding that appointment to the Bench means that "the practice of law is abandoned forever" because "if a man should step down from the privileged position of the Bench and throw off what is a sacred office to engage in the rough-and-tumble of litigious contest … he will shake the authority of the judicial limb of Government, and mar the prestige of the Courts of Justice upon which the whole structure of the State must always lean.
[11] However, Kennedy found that special circumstances existed: notably that O'Connor had not wished to return to practice but had been forcibly retired from the Bench, and it was on medical advice that he was seeking an active profession.
[12] It is true that Kennedy had an extremely poor opinion of the pre-Independence judges as a whole, recommended their removal from the Bench en bloc, and did not suggest O'Connor as one of the very few exceptions.
On the other hand, he spelt out clearly that O'Connor was free from any suggestion of corruption and, according to one report, stated that his "returning to the fold" would be a great honour to the legal profession.