Rhys practised as a barrister in Auckland specialising in civil and commercial litigation and was appointed a Queen’s Counsel in 1994. He appeared as counsel on many occasions in the High Court, Court of Appeal and Privy Council in London. He represented parties in two major commissions of inquiry and in a number of arbitrations. He also acted as legal counsel for medical and dental disciplinary tribunals and prosecuted cases for the Serious Fraud Office.
Rhys was appointed to the Court of Appeal in June 2010 after serving as a judge of the High Court in Auckland from November 2001. In that capacity he exercised a general jurisdiction, and was a Commercial List Judge for four years. He also conducted over 30 judicial settlement conferences, an ADR process available within the High Court.
Rhys retired as a judge of the Court of Appeal in February 2018. He has returned to professional practice and is available for arbitration, mediation and general advisory work.