JUNIOR PROFILE

Simon Olleson

Global 2026

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Twenty Essex
 Twenty Essex

Ranked in 1 practice area

Public International Law: The English Bar

Global Market Leaders

5 years ranked

Chambers Review

Provided by Chambers

Chambers Global Guide

Public International Law: The English Bar - Global Market Leaders

Band 1
Individual Editorial

Simon Olleson has a strong academic background in PIL and a keen interest in the law of state responsibility. He has recently advised on the PIL angles of environmental disputes and shown himself to be an expert in maritime delimitation cases and BIT arbitration. He has acted in ICJ, PCA, ICSID and ad hoc arbitration proceedings.

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Strengths

Provided by Chambers

  • Simon is really clever, his forensic analysis and the mastery of the law is evident. He produces excellent advocacy, both written and oral.

    Public International Law: The English BarChambers Global Guide

  • Simon is a go-to for me in the heavy-research-focused cases.

    Public International Law: The English BarChambers Global Guide

Ranked Barristers at Twenty Essex (114)

Asia-Pacific Region

Europe-wide

Global Market Leaders

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