[3] Thomas was educated at Feilding Agricultural High School and Victoria University College graduating with a BA and LLB in 1956, and the higher doctorate LLD in 2009.
Following many years as a partner at New Zealand law firm Russell McVeagh, he became a barrister sole and was appointed Queen's Counsel in 1981.
In 2002 Thomas was visiting fellow at the Research School of Social Sciences, The Australian National University, Canberra.
[6] Justice Thomas was brought out of retirement to become an acting Judge of the Supreme Court of New Zealand from 2005.
In the 2002 New Year Honours, he was appointed a Distinguished Companion of the New Zealand Order of Merit, for services as a judge of the Court of Appeal.