Three Crowns has been ranked in Band 1 for both Commercial Arbitration and Investor-State Arbitration in the Chambers UK 2026 rankings, maintaining its status as a top tier firm. Constantine Partasides KC is ranked again as a “Star Individual” in this year’s guide, and Gaëtan Verhoosel KC and Reza Mohtashami KC are ranked as Band 1. Leilah Bruton has moved up a band in this year’s rankings, with Manish Aggarwal ranked as “Up and Coming”.
The firm has also maintained its leading ranking in the Public International Law Guide.
“ACCLAIMED INTERNATIONAL ARBITRATION OUTFIT WITH AN IMPRESSIVE CLIENT ROSTER”
In their review, Chambers describes Three Crowns as “an acclaimed international arbitration outfit with an impressive client roster” and highlights the firm’s deep “expertise in both commercial arbitrations and investor-State disputes”. One market source notes that “Three Crowns distinguishes itself through its singular focus on international arbitration, combining strategic clarity, rigorous legal analysis and advocacy.” Our team is recognised as “incredibly responsive”, with sources noting that we are “extremely flexible and business-focused”, “proactively considering the company’s specific issues and priorities”.
The firm has also been recognised for its work in public international law. Chambers highlights its “strong pedigree in public international law matters”, noting that “the firm fields a bench of highly esteemed practitioners in this area”.
“A HEAVYWEIGHT TEAM OF ARBITRATION SPECIALISTS”
CONSTANTINE PARTASIDES KC
Constantine is one of only two practitioners identified as a “Star Individual” in the arbitration guide, the highest ranking in Chambers. The publication describes him as a “highly esteemed arbitration specialist acting for top-echelon clients in complex commercial and investment treaty disputes”. Sources emphasise that Constantine is “incredibly eminent and brilliant” and is “very attuned to the needs of the client”. One source highlights the quality of Constantine’s oral advocacy, noting that he is “is without a doubt one of the best advocates of our age”, with another adding that “he is a class act, very gifted and an eloquent speaker”. He has also been ranked for his work in public international law, with Chambers noting that he is “well known for acting in high-value disputes under bilateral and multilateral investment treaties around the world”. Constantine has appeared as appeared as lead counsel in some of the largest international arbitrations of the last two decades. He is a Member of the ICCA Governing Board and a Director of the LCIA Board.
GAËTAN VERHOOSEL KC
Gaëtan maintains his Band 1 ranking in this year’s arbitration edition, with Chambers highlighting that he “has earned an excellent reputation” for his “extensive commercial and investor-state practice”. One source emphasises that Gaëtan “is incredibly knowledgeable and practical in his approach”, with another adding that he is “is a top-ranking legal professional in all aspects”. Gaëtan also maintains a leading ranking in public international law. He has close to 25 years of experience serving as advocate or arbitrator in both commercial and investment treaty arbitrations where significant financial recoveries were at stake or novel legal issues raised. He is a member of the SIAC Court of Arbitration and was appointed to the ICSID Panel of Arbitrators by the Kingdom of Belgium.
REZA MOHTASHAMI KC
Reza has been newly ranked as Band 1 in the International Arbitration guide this year, with Chambers noting that Reza acts in “high-value disputes” with a “particular focus on the Middle East”. Sources emphasise that Reza can “advise with a helicopter view and understand the best way to manage the subject.”, adding that he “gets straight to the point and is very polished”. In his more than 25 years of practice, Reza has represented clients as counsel and advocate in arbitrations conducted under a variety of arbitral rules in many different jurisdictions.
LEILAH BRUTON
Leilah moves up a band in this year’s guide for international arbitration, in which Chambers notes that she is “experienced in acting for clients in a range of jurisdictions and under a variety of different arbitral rules”. Sources highlight that Leilah is “extremely knowledgeable”, “highly responsive, business-oriented and a pleasure to work with”, while another notes that she has “great attention to detail and has the macro-strategic vision in mind”. Leilah has extensive experience representing corporations on the resolution of complex disputes involving investment treaties and contractual relationships, with a particular focus on disputes in the oil & gas, mining, and telecoms sectors.
MANISH AGGARWAL
Manish has been recognised as “Up and Coming” in this year’s guide for international arbitration, in which Chambers emphasises his “strong experience advising across both investor-state and commercial arbitrations”. One source highlights Manish’s “strong legal acumen, commercial understanding and ability to anticipate procedural developments”, with another adding that his “attention to detail is impressive”. Manish has extensive experience of representing clients in both commercial and investment treaty arbitrations across a broad range of sectors (including energy, infrastructure, life sciences, telecommunications, and technology) and in arbitration-related court litigation.