In 1973, he graduated with an LLB from the University of Canterbury and was admitted to the bar of the High Court of Auckland in 1975.
In 1986, he left the firm and commenced practice as a Barrister Sole based in Auckland.
He has been involved in a number of high profile and controversial cases including the Equiticorp trials, where he represented a director of the failed 1980s conglomerate, and the Winebox Inquiry and subsequent judicial review.
A substantial part of his practice revolves around political work and he has represented a number of prominent New Zealand politicians from all sides of the political spectrum,[citation needed] including Winston Peters (leader of New Zealand First and deputy prime minister), Wyatt Creech (former National Party MP and deputy prime minister) and Tuariki Delamere (former New Zealand First MP and minister).
In keeping with the Henry family's wide philanthropic interests, his practice undertakes a substantial amount of pro bono litigation work – he sued the New Zealand Department of Corrections on behalf of victims of the RSA murders and has represented Pacific Island immigrant families who were the victims of unscrupulous financial buy-back schemes.