Lord Hoffmann's judgments in Investors Compensation Scheme Ltd v West Bromwich Building Society[1998] 1 WLR 898 and Chartbrook v Persimmon Homes Ltd [2009] AC 1101 are the leading general authorities in England and the Commonwealth on the interpretation of agreements. On the relationship between interpretation in domestic law and in international law, his judgment in R v Lyons [2003] AC 976 has often been cited, most recently by the Court of Final Appeal in Hong Kong. (That case concerned the interpretation of an English statute using the same words as an international treaty). Cases in which he has given judgments on the application of international law as part of English law are R v Jones [2007] AC 136 (on the incorporation of the international law on aggressive war) and Jones v Ministry of the Interior (Saudi Arabia) [2007] 1 AC 270 (on state immunity). Since 2009 Lord Hoffmann has been an arbitrator in numerous cases, some of which have raised questions of international law, and is at present the arbitrator appointed by the Government of Pakistan and by the Government of Albania in two arbitrations under an investment treaty and the Energy Charter respectively.

In the period since 2009 he has sat as an arbitrator in over sixty arbitral proceedings under the rules of the ICC, the LCIA and ICSID in disputes concerning commercial, property, intellectual property rights, private international law and public international law.

Positions and offices include:

Chairman of the Bank of England Financial Services Law Committee, an independent committee established and sponsored by the Bank of England. FMLC's role is to identify issues of legal uncertainty, or misunderstanding, present and future, in the framework of the wholesale financial markets which might give rise to material risks, and to consider how such issues should be addressed.
Chairman of the "Hoffmann Commission", constituted by MTN Group to investigate claims of corruption in relation to MTN's bid to participate in the second mobile phone network in Iran.
Honorary Professor of Intellectual Property Law, Queen Mary University of London.
Visiting Professor, Faculty of Law, Oxford University.
Chair, Institute of Intellectual Property Research Council.
Honorary fellow, Queen's College, Oxford.
Honorary fellow, University College, Oxford.
Honorary fellow, Chartered Institute of Taxation.

• Leonard Hoffmann QC possesses in-depth knowledge of commercial law and has extensive experience in both commercial and investment-treaty cases. (Who's Who Legal - UK Bar: Arbitration 2020)
• Lord Hoffmann QC wins high acclaim for his long-standing practice as an arbitrator. He is often selected for LCIA and ICC arbitrations, as well as to sit on ad hoc tribunals. Sources describe him as "a legendary figure," adding that he is "an extremely effective lawyer and arbitrator." (Chambers & Partners Europe 2020: Most In Demand Arbitrators - Europe-wide)
• Lord Hoffmann QC of Brick Court Chambers maintains an excellent reputation for his investment treaty and commercial arbitration expertise. He is highly sought after to handle disputes under all major arbitral rules. A peer advises: "He has the capability of focusing on the relevant issues immediately which is always impressive." (Chambers & Partners Global 2020)
• "Absolutely peerless and intellectually brilliant." (Legal 500 2020)
• Brick Court Chambers’ Leonard Hoffmann QC is one of the pre-eminent names in our research who is commended by peers across the market for his sheer depth of understanding of investment treaty disputes, and his assured approach as arbitrator. (Who's Who Legal - UK Bar: Arbitration 2019)
• "He is hugely respected and incredibly hard-working." "He's supremely sharp, very fair and you can see the weight that his opinion as a former judge carries." (Chambers & Partners Europe 2019: Most in Demand Arbitrators - Europe-wide)
• "He has an incredible reputation and I totally understand why" "Absolutely on the ball. He has a very incisive mind and is a good person to work with." (Chambers & Partners UK & Global 2019)
• "He’ll ask a question and that’s the end of the case." (Legal 500 2018-19)
• Leonard Hoffmann QC is “absolutely superb” according to sources, who consider him “in the pantheon of arbitration practitioners”. (Who's Who Legal - UK Bar: Arbitration 2018)
• "A star by virtue of his career on the Bench. Absolutely top quality, charming and brainy." (Chambers & Partners 2018)
• "A first-class arbitrator." (Legal 500 2017)
• "He is everything that you can possibly want from an arbitrator: he's merit driven, fast and in control of the proceedings." (Chambers & Partners 2017)
• The vastly experienced and esteemed Lord Hoffmann QC of Brick Court Chambers in London continues to work as an arbitrator in international disputes. "He is an absolutely superb lawyer and is incredibly collegiate," report sources. (Chambers & Partners Global 2016)
• "Absolutely peerless." (Legal 500 2016)
• “Lord Hoffmann QC of Brick Court Chambers undertakes instructions on disputes relating to shipping, IP, property and public international law, as well as other areas. He is a former Lord of Appeal in Ordinary. Sources are full of praise, saying: "He has a stellar reputation and is a great intellectual. He is the right person for arbitrations involving intricate pieces of law."” (Chambers Global 2015)
•  “Lord Hoffmann of Brick Court Chambers is a heavyweight arbitrator renowned for his phenomenal intellect and gravitas. He is based in London and comes recommended for difficult arbitrations involving technical points of law. "He is very efficient and gets right to the heart of the case," comments one observer. His experience as arbitrator encompasses ICC, LCIA and ICSID proceedings relating to IP and to private and public international law.” (Chambers Global 2015)
• “Leonard Hoffmann is a “legend” of the UK arbitration bar who brings “great experience and intellect” to the arbitrator role across a range of commercial matters.” (Who's Who Legal UK Bar 2015) 
• "Intimidatingly good; a counsel’s dream and nightmare rolled into one." (The Legal 500 2014)
• Another at this stable is Lord Hoffmann QC, who is "just legendary, and one of the pre-eminent legal minds of his generation." He is ever-popular as an arbitrator, and is highly respected for his proven expertise in the field. Sources comment that he is "as sharp as can be, incredibly diligent and hard-working" in the role of arbitrator. (Chambers & Partners 2013)