Vernon is the founder and leader of the Sustainable New Zealand Party. He is a practising barrister, specialising in criminal defence. He was elected for two terms as a member of the Waitematā Local Board of Auckland Council. He is a certified resource consent commissioner and holds a Master of Laws degree with first class honours in environmental law.
He founded the party out of a concern that, for too long, a vote for the environment has also meant a vote to the left of Labour and a grab-bag of fringe issues. Sustainable New Zealand has been formed to put sustainability at the centre of politics and save the environment from being just a left-wing issue.