Slide ABOUT JOHN C. LENZEN, FCIArb International Arbitrator, Mediator,
Insurance Expert & Consultant


John C. Lenzen, FCIArb is an international arbitrator, mediator, insurance expert and consultant. For twenty-five years, he served the insurance industry as outside counsel and in a variety of senior Legal and Claims roles, principally based in Bermuda. These included General Counsel to several insurance and reinsurance companies, General Counsel to and Head of Claims for the largest Bermuda-based insurer and its Dublin subsidiary, and fifteen years as Worldwide Head of Litigation, and Chief Litigation Counsel, Global Claims to the world’s largest publicly traded property and casualty insurer.

Practice Focus & Expertise

John regularly serves as an arbitrator in international commercial disputes, including as sole or Chair/third arbitrator, and has authored numerous Final Awards. He has also had direct responsibility for the hands-on management of many international and multi-jurisdictional arbitrations in Bermuda, England and the United States. At least twenty of these proceeded to an Award on the merits, and the vast majority were disputes over at least $100 million. Almost all of these arbitrations involved a multiplicity of arguably applicable procedural and substantive laws, and many also entailed competing litigations as to predicate jurisdictional issues. Indeed, some required parallel or even subsequent challenges to the arbitral process itself, including the seminal Halliburton v Chubb [2020] UKSC 48, which was ultimately resolved by the Supreme Court of the United Kingdom.

John also has extensive experience personally resolving many complex, nine-figure disputes through mediation and principal-to-principal negotiations, and successfully employing creative negotiating strategies for challenging multi-party disputes implicating up to ten figures and involving numerous counsel and perspectives, and dozens of parties. More broadly, he has fairly assessed, determined and resolved countless high-severity claims under commercial policies involving Casualty (Bermuda Form, Claims Made and Occurrence), D&O, E&O, Property, Political Risk, Financial Solutions (finite cover), Aviation, Satellite, Reinsurance and Retrocessions. These claims were based on massive underlying losses spanning the globe. With this background, a large part of John’s career has been devoted to counseling executives, underwriters and claims professionals on best practices, likely outcomes and unconventional approaches to achieve exceptional resolutions.

John is available to consult confidentially and/or to provide expert testimony where necessary and appropriate. He has testified repeatedly as the key witness in high-stakes litigation and been cross-examined by both preeminent American litigators and English Queen’s Counsel (as they then were).


Lenzen ADR
Principal & Chief Executive Officer

Chubb (formerly ACE) Group
Worldwide Head of Litigation
Chief Litigation Counsel, Global Claims

Chubb Bermuda Insurance
General Counsel & Secretary
Head of Claims & Chief Claims Counsel

ACE INA Overseas Insurance
General Counsel

Paget Reinsurance International
General Counsel

Connell Foley
Insurance-Coverage Litigator

Superior Court of New Jersey,
Appellate Division

Judicial Clerk


  • New York
  • Texas
  • Michigan
  • New Jersey (Resigned)
  • England and Wales (Solicitor)
  • Supreme Court of the United States
  • Various United States Federal Trial and Appellate Courts


University of Michigan
Ross School of Business

M.B.A. (with High Distinction) Finance, Corporate Strategy & Business Economics

Rutgers University
Rutgers University School of Law


Rutgers University
Rutgers College




Lawful Permanent Resident, U.S.


  • Fellow, Chartered Institute of Arbitrators (FCIArb)
  • Accredited Mediator, Centre for Effective Dispute Resolution (CEDR)
  • Member, Users’ Council, London Court of International Arbitration (LCIA)
  • Panel Member, ARIAS (UK)
  • Certified Neutral Arbitrator, ARIAS-US
  • Certified Mediator, ARIAS-US
  • International Bar Association
  • American Bar Association
  • Law Society of England and Wales
  • New York State Bar Association
  • State Bar of Texas
  • State Bar of Michigan