Three Crowns maintains its Band 1 International Arbitration positions in both Commercial and Investor-State Arbitration in the Chambers UK Guide – 2021 rankings. Constantine Partasides QC, Gaëtan Verhoosel, Reza Mohtashami QC, and Carmen Martinez Lopez are recognised individually, with Partasides garnering “Star Individual” honours. In addition, the firm maintains a leading ranking in Public International Law.


In once again naming Three Crowns a top practice in International Arbitration, Chambers highlights that the firm is an “acclaimed international arbitration boutique with an impressive client roster” featuring both corporate and governmental clients in a wide variety of sectors, including energy, natural resources, financial services, telecoms, and engineering.

Sources note Three Crowns is “an absolutely exceptional firm” with “a top-tier reputation.” Chambers also recognises that the firm is “well-versed in handling BIT claims and disputes brought under the Energy Charter Treaty.”

Additionally, the firm maintains its leading ranking in Public International Law.



Partasides is one of only two practitioners identified as a “Star Individual,” the highest ranking in the Chambers Guide. Commenters note he “is simply superb and one of the best advocates of this generation,” and “extremely polished, a master of the detail and remarkably procedurally astute.” Partasides has appeared as counsel in some of the largest commercial arbitrations of the past decades and his broad practice includes inter-State and investment treaty disputes. He has published extensively on international arbitration and international law.


In maintaining his ranking for 2021, Chambers notes Verhoosel’s “excellent reputation for his extensive commercial and investor-state practice, handling arbitrations seated across the world.” As one client notes to the publication, he is “very sharp, articulates his arguments well and is good in devising the right legal strategy while also convincing the tribunal.” Verhoosel has served as advocate and as arbitrator in numerous commercial and investment treaty arbitrations where significant financial recoveries were at stake or novel legal issues raised.


Mohtashami also maintained his ranking for 2021, with Chambers noting his work for “various entities in high-value disputes.” One commenter notes, “He is the real deal, especially when it comes to his business acumen and ability to craft strategy.” Mohtashami has represented clients as counsel and advocate in more than 80 arbitrations conducted under a variety of arbitration rules in many different jurisdictions. He has particular expertise in disputes arising in emerging markets and is a highly sought-after specialist in the Middle East, with a focus on the telecoms, energy, and infrastructure sectors.


Martinez Lopez maintains her ranking in the Guide for 2021. Known for her “Latin America expertise” and “knowledge of Spanish law matters,” she has appeared as advocate in numerous investment treaty and commercial arbitrations, both under the rules of the major arbitral institutions and ad hoc, across a variety of jurisdictions. As one commenter notes, “She has worked on some of the biggest cases of all time and is a quality lawyer.”


Three Crowns is a firm committed to excellence in international arbitration and international law. Founded by practice leaders with decades of experience across many different international firms, it is recognised as one of the premier arbitration practices in the world. Its clients—including Fortune 500 companies and sovereign States—entrust the firm with their most important disputes.

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