Three Crowns has maintained its status as a top tier firm and has been ranked in band one for both Commercial Arbitration and Investor-State Arbitration in the Chambers UK 2022 rankings. Constantine Partasides QC, Gaëtan Verhoosel, Reza Mohtashami QC, and Carmen Martinez Lopez have been individually ranked. The firm also maintained its leading ranking in the Public International Law guide.


Chambers highlighted that Three Crowns “fields a heavyweight team of arbitration specialists with expertise in both commercial arbitrations and investor-State arbitrations”, noting the team comprises “well-known names from the energy, natural resources, financial services, telecoms, and engineering sectors”. Market commentators state, “they are top notch for arbitration” and “institutional clients rate them highly”, adding that “they are formidable”. In relation to investor-State arbitration, a client commended Three Crowns for its “stellar investment treaty practice” with the publication adding that the team is “well versed in handling BIT claims and disputes brought under the Energy Charter Treaty”.

The firm has also been recognised for its work in public international law, with the guide describing its “strong pedigree in public international law matters”, in which it “fields a bench of highly esteemed practitioners in the area”.



Constantine is one of only two practitioners identified as a “Star Individual,” the highest ranking in the Chambers guide. The publication highlights that he is a “highly esteemed arbitration specialist acting for top-echelon clients” whilst commenters note “he is a star” and “he is a very polished advocate, and as an arbitrator he is experienced and able”. Constantine was also described as a “talented advocate, and his focus on arbitration allows great insights into arbitration practice and procedure”. He has also been ranked for his work in public international law. Constantine 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 was recently appointed to the LCIA Board, and has published extensively on international arbitration and international law.


In maintaining his ranking for 2021, Chambers notes that Gaëtan has “earned an excellent reputation for his extensive commercial and investor-State practice” with clients stating “he is excellent”, “he has been a very effective advocate”, and that “he has world-class experience and skills”. Gaëtan 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. He was recently appointed as a Member of the SIAC Court of Arbitration.


Reza has moved up a ranking and is now recognised in band 2 in the Chambers guide, in which commentators note that “he is extremely highly regarded”, he has “a good mix of commercial and treaty work”, describing him as “strong”, “excellent”, and “brilliant”. Reza 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.


Carmen maintained her ranking again this year, in which she is “credited for her Latin American expertise” and that she is “sought out for her knowledge of Spanish law matters”. A commentator describes her as a “bright and effective advocate”, with Chambers adding that she is “experienced in handling significant arbitrations in the oil and gas sectors”. Carmen 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.

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