Justice McHerron graduated from the University of Otago with a BA in English literature in 1994 and an LLB in 1996. From 1996 to 1999 he worked at Russell McVeagh in Wellington before moving to the Crown law Office. Justice McHerron joined the independent bar in 2006 specialising in public law and commercial litigation.

Since 2015 he has been a part‑time adjudicator with the Motor Vehicle Disputes Tribunal, and from 2018 to 2023 he was a member of the Rules Committee, as a New Zealand Law Society nominee. His appointment as a High Court Judge will take effect on 19 March 2024, and he will sit in Wellington.