William Thomas KC

Ranked in 2 Practice Areas

Band 1

Public International Law

Global Market Leaders

6 Years Ranked

Band 2

International Arbitration

4 Years Ranked

Ranked in Guides

UK 2026

About

Provided by William Thomas KC

Global

Practice Areas

Will specialises in international commercial arbitration, investment arbitration and public international law, and has particular expertise in the extractives, TMT and projects sectors. He has represented parties, as counsel and advocate, in numerous institutional and ad hoc arbitral proceedings, including before ICC, LCIA, CAS, ICSID and UNCITRAL tribunals. Will has also acted for parties in proceedings before the International Court of Justice and the Iran-US Claims Tribunal.

Career

Will holds a degree from the University of Cambridge, and is an English solicitor-advocate and Queen’s Counsel. He lectures annually on international law at King’s College, London and Sciences Po, Paris. He speaks English and French.

Chambers Review

Provided by Chambers

Chambers Global Guide

Public International Law - Global Market Leaders

Band 1

Individual Editorial

William Thomas KC heads the firm's global public international law group and he is a well reputed name in the field, known for his longstanding experience handling inter-state and investor-state disputes. He is often seen acting in landmark cases before various major courts and tribunals, including the ICJ, and is noted as a dedicated PIL advocate.

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International Arbitration - UK

Band 2

Individual Editorial

William Thomas KC's arbitration practice includes complex disputes arising from the telecoms industry. He expertly acts for both claimants and sovereign states in big-ticket BIT disputes.

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Strengths

Provided by Chambers

William Thomas has great judgement.

Public International Law respondent
Chambers Global Guide

William Thomas is a brilliant lawyer.

Public International Law respondent
Chambers Global Guide

William is very good at spotting trends in the market. He has excellent judgement and is great at packaging advice in a way that is digestible for clients.

Public International Law respondent
Chambers Global Guide

William provided great strategic insight, flair and advocacy.

International Arbitration respondent
Chambers Global Guide

William is very commercially savvy and a great team leader.

International Arbitration respondent
Chambers Global Guide

William is switched on to all of the strategically important elements of a case and is able to offer solutions.

International Arbitration respondent
Chambers Global Guide

He is an extremely solid, dependable practitioner; he is unrufflable.

International Arbitration respondent
Chambers Global Guide

William Thomas has great judgement.

Public International Law respondent
Chambers Global Guide

William Thomas is a brilliant lawyer.

Public International Law respondent
Chambers Global Guide

William is very good at spotting trends in the market. He has excellent judgement and is great at packaging advice in a way that is digestible for clients.

Public International Law respondent
Chambers Global Guide

William provided great strategic insight, flair and advocacy.

International Arbitration respondent
Chambers Global Guide

William is very commercially savvy and a great team leader.

International Arbitration respondent
Chambers Global Guide

William is switched on to all of the strategically important elements of a case and is able to offer solutions.

International Arbitration respondent
Chambers Global Guide

He is an extremely solid, dependable practitioner; he is unrufflable.

International Arbitration respondent
Chambers Global Guide

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Africa-wide

Corporate/M&A & Private Equity

Pervez Akhtar

Band 2

William Thomas KC

Global Guide 2026

Public International Law + 1 more ranking

About

Practice Areas

Career

Chambers Review

Chambers Global Guide

Public International Law - Global Market Leaders

Individual Editorial

International Arbitration - UK

Individual Editorial

Strengths

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Africa-wide

Austria

Bahrain

Belgium

Public International Law

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