You can check out most of the cases he has appeared in by visiting the Ministry of Justice's Judicial Decisions Online website and searching for Coleman in the counsel box. He has been arguing tax cases since 1991 so as over 28 years’ experience. He knows his way around a court.
This website also contains a partial list of the cases he has appeared in as well as copies of some of the judgments. The cases James has argued include a large number of the leading cases in terms of New Zealand tax law. He is truly a tax expert.