Overview
Guillaume is an all-round litigator specialising in international arbitration and cross-border litigation. He also regularly works on criminal, regulatory and internal investigations as well as compliance matters, with a specific focus on corporate sustainability and ESG. Guillaume’s experience spans various sectors and industries, in particular the financial services, construction, (post-)M&A, commercial contracts, restructuring and insolvency, energy and pharmaceutical sectors.
Guillaume has a decade of experience representing clients as counsel in commercial and investment arbitration as well as related state court proceedings. He has also been appointed as an arbitrator and as a tribunal secretary under the ICC, LCIA, CEPANI and NAI rules. He is the co-chair of the Belgian organisation of under 40-year-old arbitration practitioners (CEPANI40), a member of the board of directors and diversity and inclusion steering committee of the Belgian arbitration association (CEPANI), and a member of the ICC Commission on Arbitration and ADR. 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 corporate sustainability/ESG, and broader compliance matters (including international sanctions and white collar crime). He lectures on ESG at the Université libre de Bruxelles (ULB). He is a member of the ICC Working Group on Business and Human Rights and of the ICC Commission on Corporate Responsibility and Anticorruption. He contributed the section “Business Integrity” to the 2nd edition of the United Nations Global Compact Guide for General Counsel on Corporate Sustainability and he is the co-editor of the first textbook on Belgian law and sustainability.
Guillaume is recognised by clients and peers in the leading legal directories, including Chambers & Partners, Legal500, Lexology Arbitration (former Who is Who Arbitration) and Leaders League, where he is his described by clients as a “brilliant” and “extremely intelligent” lawyer “with excellent strategic insights to bring disputes to the best end” (Chambers & Partners 2025), “a rising star at the bar, who combines technical excellency with pragmatic strategic advice” and whose “service is unbeatable” (Legal500 2023), “a highly sought-after counsel for major domestic and multi-national clients regarding ESG liability risks, ESG compliance, and sustainability regimes” (Legal500 Green Ambassadors: Europe 2025).
Work Highlights
Guillaume has worked on a wide range of business-critical disputes. Those that can be disclosed include representing and advising:
- an Asian multinational in a USD 100M post-M&A ICC arbitration
- a global financial institution in a USD 250M CEPANI arbitration and parallel Belgian court proceedings
- a global bank, in Belgian and English court proceedings pertaining to the enforcement of an arbitral award against an Asian State and attachments over assets worth US$22bn
- an African State in the Belgian annulment proceedings of a €1bn investment arbitration award
- a global bank before the EU institutions, an LCIA arbitral tribunal, the European Court of Human Rights and local courts in its capacity as creditor for an amount of US$1bn of an Eastern European group benefitting from protectionist measures adopted by its home State
- various multinationals as global ESG counsel, covering the full spectrum of sustainability matters (ESG litigation and greenwashing, supply chain due diligence, sustainability reporting, etc.)
- a Belgian multinational in bribery and money-laundering parallel investigations across five jurisdictions
Admissions