Image of Guillaume Croisant

Guillaume Croisant

Litigation, Arbitration & Investigations Managing Associate, Brussels

"I assist clients with their business-critical disputes, specialising in international and complex arbitration, litigation and investigation."


Professional experience

Education & qualifications


Guillaume is an all-round litigator specialising in international arbitration, cross-border litigation and multijurisdictional criminal and regulatory investigations. 

Guillaume has extensive experience in commercial and investment arbitration as well as related state court proceedings. He has been appointed as an arbitrator and as a tribunal secretary under the ICC, LCIA, CEPANI and NAI rules. He is a member of the ICC Commission on Arbitration and ADR and of various arbitration associations (including the Steering Committee of CEPANI40). He undertook a one-year secondment in the international arbitration practice of our London office in 2017-2018.

Guillaume also devotes a substantial part of his practice to ESG, business and human rights and broader compliance matters (including international sanctions and white collar crime). He is a member of the ICC Working Group on Business and Human Rights and the ICC Commission on Corporate Responsibility and Anticorruption. He contributed the section “Business Integrity” to the 2nd edition of the Guide for General Counsel on Corporate Sustainability (United Nations Global Compact).

Guillaume lectures on private international law and advocacy in international arbitration at the Université libre de Bruxelles (ULB). He is the co-editor in chief of Belgium’s leading business law journal (Revue de Droit commercial belge / Tijdschrift voor Belgisch Handelsrecht). He is the author of numerous contributions in treaties and legal journals, and he regularly discusses topical subjects related to his practice with the general and specialised press (Financial Times, Reuters, The Guardian, Politico, Global Arbitration Review, ESG Investor, etc.).

Work highlights

Guillaume has worked on a wide range of business-critical disputes. Those that can be disclosed include representing and advising:

  • Bank of New York Mellon (BNYM), in Belgian and English court proceedings, after BNYM froze the assets of the National Fund of Kazakhstan, worth some US$22bn, as a result of a third party garnishment order obtained by investors attempting to enforce an arbitral award against Kazakhstan
  • ENGIE before the Belgian Constitutional Court and civil courts in proceedings arising from the yearly taxes of c. €500m levied by the Belgian State on the nuclear energy sector
  • an Asian holding company in a €100m ICC arbitration
  • an African State in the Belgian annulment proceedings of a €1bn investment arbitration award
  • a Belgian multinational in bribery and AML parallel investigations across five jurisdictions
  • a Belgian financial institution as respondent in parallel ICC arbitration proceedings and Belgian court proceedings on the disconnection of undertakings from its network, in alleged breach of competition law and EU sanctions law
  • a global financial institution in a US$250m CEPANI arbitration and parallel Belgian court proceedings
  • a global bank before the EU institutions, an LCIA arbitral tribunal, and local courts in its capacity as creditor (for an amount of c. US$1bn) of an Eastern European group in financial distress benefitting from protectionist measures adopted by its home State

Professional experience

Guillaume has worked on a number of pro bono and community investment initiatives of the firm, including by delivering trainings on business and human rights in Kenya (with Advocates for International Development), contributing to the 2nd edition of the Guide for General Counsel on Corporate Sustainability (with the United Nations Global Compact), drawing up a European database of asylum law (with the European Council on Refugees and Exiles; finalist of the 2016 European Award for Exemplary Partnership in the Public Interest) and representing aisle seekers before the European Court of Human Rights (Rule 39 Initiative of the Italian Coalition for Civil Liberties and Rights).

Education & qualifications

Guillaume was admitted to the Brussels bar in 2014 (Prix George Boels).

He holds a Magister Juris from the University of Oxford (Brasenose College, Wiener Anspach Foundation Scholar) and a Bachelier en droit and a Master en droit from the Université libre de Bruxelles (Prix René Marcq, Prix André Bruyneel, Premier Prix d’Excellence).

Guillaume completed the ESG Accelerator Programme of the University of Oxford (Saïd Business School) in 2021.

He speaks French, English and Dutch.