Prior to entering Parliament he qualified as a Barrister and Solicitor and practiced in criminal law.
[1] Campbell was the Alliance candidate for the 1998 Taranaki-King Country by-election, and claimed to have "played some small part in bringing about the closer working relationship between Labour and the Alliance as a result of that by-election.
He initially committed to appearing on the Alliance's party list but withdrew on 11 June 2002.
[7][8][9] Since leaving Parliament Campbell has worked as a Supervising Solicitor at Community Law Canterbury.
[1] Campbell ran again as an Alliance candidate in the Wigram electorate, seeking to be the replacement for out-going MP Jim Anderton but lost, coming fourth, to Megan Woods, a former member of the Alliance & Progressive parties standing on a Labour ticket.