Marie Stoyanov

Practice Areas

Marie specialises in commercial and investment treaty arbitration. Marie is the Global Head of Arbitration and the Co-Head of the Energy Sector. She has advised and represented clients in arbitrations throughout the world, both ad hoc and under all the major institutional rules, including the ICC, LCIA and ICSID Rules in which she has particular expertise. 

Marie has substantial experience across all market sectors but her practice focuses particularly on infrastructure, energy, and natural resource disputes, with expertise in disputes arising across the African continent.

With clients that include both international investors and sovereign States, Marie regularly appears as advocate before renowned international tribunals arguing extremely complex cases, often with hundreds of millions of dollars at stake. Marie also sits as an arbitrator herself and has written and spoken regularly about international investment and arbitration.

In addition, Marie has also advised various clients on how best to structure their investment in Africa, Eastern Europe and Asia, in order to take advantage of protections offered by investment treaties and foreign investment laws.

After graduating from ESSEC, Marie studied law and was admitted to the Paris bar in 2003. As a French qualified lawyer, she is naturally used to working in all civil-law environments, in particular those whose law is directly derived from French law (e.g. Algerian law, Egyptian law, Moroccan law, UAE law).

A member of the Executive Board of the European Federation for Investment Law and Arbitration (EFILA), Marie is also an Advisory Board member of the publication Investment Claims, which is published by Oxford University Press.

Band 4

Chambers Global 2024 - (International Arbitration)

"Marie Stoyanov has excellent advocacy skills and the ability to tackle complex cases."

Chambers Global 2024 - (International Arbitration)

"Marie is an excellent arbitration lawyer. She was excellent in cross-examinations, smart and pleasant."

Chambers Global 2024 - (International Arbitration)

Band 4

Chambers Global/Europe 2023 - France (International Arbritation)

Band 5

Chambers Europe-wide 2023 - France Arbritation (International )

"Marie Stoyanov of Allen & Overy LLP specialises in assisting investors with claims under the Energy Charter Treaty. She also handles investment arbitration on behalf of states."

"Marie Stoyanov is very solid, hard-working, and has a good advocacy style."

Chambers Global/Europe 2023 - France (International Arbritation)

"Paris-based Marie Stoyanov moves into the rankings following strong feedback from market observers. Sovereign states regularly mandate Marie Stoyanov for her expertise in ICSID proceedings as well as ECT and BIT claims. She also represents prominent corporates in ICC arbitrations."

"She has a fierce intellect."

"Marie Stoyanov is very efficient in cross-examination and well prepared."

"She is hard-working and has a good advocacy style."

"She is an awesome pleader, easy to follow and always prepared for counterarguments."

Chambers Europe-wide 2023 - France Arbritation (International)

Leading Individual

Legal 500 EMEA 2023 - France (Dispute resolution: International arbitration)

"Marie Stoyanov is a remarkable lawyer."

Legal 500 EMEA 2023 - France (Dispute resolution: International arbitration)

"Marie Stoyanov is remarkably intelligent, sharp and professionally competent with wideranging expertise."

Legal 500 EMEA 2021 - France (Dispute resolution: International arbitration)

"Next Generation Partner"

Legal 500 EMEA 2020 – France (DISPUTE RESOLUTION: INTERNATIONAL ARBITRATION)

Band 4

Chambers Global/Europe 2020 - France (International Arbitration)

Marie Stoyanov of Allen & Overy LLP regularly advises on investment treaty arbitrations, acting for both the states and private investors. Her practice includes handling cases brought under the Energy Charter Treaty. Clients comment: "She is very accessible and has a real commitment to service."

Chambers Global/Europe 2020 - France (International Arbitration)

* * - Arbitrage international

ODA 2019 - France

She is "diligent and impressive in terms of her knowledge of the subject and of the proceedings."

Chambers Global 2018 - France (Dispute Resolution: International Arbitration)

"Next Generation Lawyer"

Legal 500 2017 - France (Dispute Resolution/International Arbitration)

Marie was awarded the “Star of Tomorrow” distinction for International Arbitration by French newspaper Les Echos, Marie is described by Chambers & Partners as having “particular focus on investment treaty and related disputes”, in which context she is “very sharp in understanding and reaching the crux of even the most complicated issues”

Chambers 2017 - France (Dispute Resolution: International Arbitration)

"Marie Stoyanov is 'very sharp in understanding and reaching the crux of even the most complicated issues'."

Chambers 2017 - France (Dispute Resolution: International Arbitration)

"Marie Stoyanov is described as 'an outstanding, talented lawyer'."

Chambers 2016 - France (Dispute Resolution: International Arbitration)