In the 2005 Queen's Birthday Honours, O'Brien was appointed an Officer of the New Zealand Order of Merit, for services to rugby as a referee.
[1] In 2007, O'Brien, in his capacity as Rugby World Cup Chief of Officials, defended criticism of the refereeing of Wayne Barnes in the France versus New Zealand quarterfinal.
[6] During the 2011 Rugby World Cup O'Brien publicly defended referee Alain Rolland's decision to issue Wales Captain Sam Warburton a straight red card during their semi final match against France stating "Alain Rolland's decision to issue a red card was absolutely correct in law and in keeping with the clear instructions that match officials have received in recent years regarding dangerous tackling.
"[7] In May 2012 he was released as head of the Referee Board and substituted by a commission of four members[8] O'Brien was elected to the Invercargill Licensing Trust (ILT) in 2016 and re-elected in 2019, topping the poll both times.
[9] Following the resignation of deputy mayor Toni Biddle from the Invercargill City Council, O'Brien announced his intent to contest the resulting by-election.