Bretton Woods Law - Lee Marler
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Bretton Woods Law - Antje Kunst
Bretton Woods Law - Ludovica Moro
Bretton Woods Law - Joseph Oppenheimer

William Thomas


William A L Thomas (




  • Direct Access Accredited



  • Public International Law
  • Rule of Law

Practice Areas

William recently returned to private practice as a barrister, having served as a legal advisor/senior legal advisor for two major international organisations in the Balkans for over 10 years. Having advised at Minister/Ambassador-level he is adept at operating at the sensitive intersection of law, diplomacy, policy and politics. He brings a wealth of experience in the following areas:

Legislative/Regulatory Reform

William was responsible for the inception and execution of a number of legislative/regulatory projects in Bosnia and Herzegovina. Most notably, serving initially as international co-chairperson of Bosnia and Herzegovina Defence Reform Commission Legal Team, he led the design and drafting of the highly complex legislation and long-term implementing arrangements required to merge three defence establishments. He also advised the United Nations on the legal aspects of local and international security arrangements in Kosovo as well as lectured at the NATO School in Germany on so-called ‘rule of law operations’.

International Administrative Law

Having worked for international organisations, William brings a unique perspective to his private practice within this field. He has first-hand experience of solving a range of regulatory, financial, status, employment and liability issues for such organisations. He also has a nuanced understanding of international organisations’ privileges and immunities apply, and advised on specific cases and negotiated with receiving state authorities in this context.

Treaty Law

William’s work in the Balkans involved advising senior international officials on the application and interpretation of treaties most notably the military aspects of the General Framework Agreement for Peace in Bosnia and Herzegovina, a sub-regional arms control agreement and other international agreements concerning the status of military and civilian personnel when serving abroad.


  • Bachelor of Arts (History) – University of Cambridge
  • Graduate Diploma in Law – City University, London
  • Bar Vocational Course – Inns of Court School of Law, London
  • Master of Laws (Public International Law) – University of London


  • Awarded NATO non-Article 5 medal
  • Master of Arts – Cambridge University
  • Member of the British Institute of International and Comparative Law
  • Member of the Public Access Bar Association
  • Member of Inner Temple (called to the Bar of England and Wales in 1998)
  • United Nations System and Human Rights Courses – United Nations University, Japan


Having briefly worked in the advertising industry including with the Financial Times, William decided on a career in law. He first practised as a barrister from 1998-2001 focusing on housing and family law matters in which he typically represented local government authorities. He appeared in a range of courts and tribunals up to and including the High Court, and also represented clients in consumer credit, employment, contract, negligence and company law matters.

However, it was his abiding interest in international relations that led him to study for a Masters in Public International Law in 2002-2003 at London University (UCL). There he studied Foreign Relations Law, United Nations Law, the Law of Armed Conflict and the Use of Force (LSE), and Islamic Law (SOAS). Since then and before returning to practice in 2017, William worked for the Organisation for Security and Co-operation in Europe’s Mission to Bosnia and Herzegovina (where he was a trial monitor/report writer on criminal procedure and war crimes prosecutions) and the NATO presence in Bosnia Herzegovina.

Marler is an established expert in the rule of law and public international law generally. I have seen him at work over the years and he is impressive. A barrister with a quick mind, an eloquent tongue and a talent with a pen, as well as having a keen sense of humour. I selected him to be my General Counsel at EQ-G for a reason.

General Sir David Richards GCB CBE DSO (former UK CDS and now Lord Richards of Hertsmonceux)

Lawyers in private practice with talent and expertise in resolving MDB sanctions cases are few and far between, but Lee Marler is one of them. He has proven himself time and again to be knowledgeable and highly effective. He is also a fine advocate and draftsman, and this is why I instruct him – where necessary – to assist IACD in its efforts to curb corruption on AfDB financed projects.

Anna Bossman, Director, AfDB’s Integrity and Anticorruption Department (“IACD”)

An unparalleled blend of legal expertise in the area of International Administrative Law and an understanding of the mindset and functioning of legal departments at international institutions.”

Zbigniew Kominek, Former Chair, EBRD Staff Council