- James Kessler QC is particularly interested in taxation of foreign domiciliaries, offshore entities of all kinds, and trusts, wills and charities. Other interests include prosecution of tax crime in complex cases, particularly along the avoidance/evasion faultline, and freedom of information. Recent cases include: Embiricos v Revenue & Customs  UKFTT 236
- James has practiced as a barrister since 1985 and was appointed QC in 2003. He is also a member of the Bar of Northern Ireland.
- He is in Band 1 in Chambers Directory in the Private Client Tax category, with a reference to "acumen and remarkable thoroughness of thought" and in Band 1 in the Legal 500 directory which comments: "The leading expert on the taxation of non-domiciled individuals."
- James is one of the founders of the Society of Trust and Estate Practitioners, for whom he drafted the STEP Standard Provisions, and a fellow of the Chartered Institute of Taxation.
- James has received the Geoffrey Shindler Award for Outstanding Contribution to the Profession (STEP Private Client Awards, 2011).
James has appeared in many leading cases including:James Kessler QC and Ross Birkbeck - Embiricos v HMRC 
Ardmore v HMRC  (location of source of interest for UK tax purposes - citability of unpublished Special Commissioners decisions)
R v IRC ex p. Unilever (Judicial review of HMRC)
IRC v Dawson (Trust residence)
Wensleydale's Settlement Trustees v IRC (Double taxation treaties and trusts)
R v Dimsey & Allen (Family home and benefits in kind; HMRC prosecution)
Phizackerley v HMRC (Nil rate band discretionary trusts)
Burns v HMRC (Transfer of assets abroad)
Books by James Kessler QC:
James is the author of three major works:
There are at present nine foreign-law editions of Drafting Trusts and Will Trusts: