A powerful presence in intellectual property law, Warwick commenced practice as a barrister sole in 2000 after more than 10 years as a litigation partner at Chapman Tripp. He was originally admitted as a barrister and solicitor of the High Court of New Zealand in 1974.

In intellectual property litigation Warwick's work has seen a particular emphasis on trade mark and passing off disputes, domain name and Internet issues, and copyright disputes. His arbitration work includes international appointments as a Panellist for the World Intellectual Property Organisation, deciding disputes over domain names and on a number of occasions he has been appointed by WIPO to chair international panels handling such disputes. He is also one of WIPO's arbitration "neutrals", available to act as arbitrator in disputes arbitrated under the WIPO Arbitration Rules.

Warwick's commercial litigation includes extensive experience in a wide variety of contract and tort claims, while he has also secured a reputation in construction law, including extensive involvement over recent times years in New Zealand's 'leaky homes' litigation.

He is a Fellow (Arbitration) of the Arbitrators' & Mediators' Institute of New Zealand Inc., and a member of the Institute's Panel of Arbitrators.