Along with Barry MacDonald, Treacy challenged the ruling that barristers must swear allegiance to the Queen, arguing successfully that lawyers who held nationalist views should be exempt from this requirement.[3]
Personal life
In 2009, following the discovery of a pipe bomb nearby, Treacy moved from his Belfast home due to security concerns.[3]
In 2018, he resigned from the Privy Council, only a few months after his appointment.[4]