Sjef Janssen

Sjef has substantial experience in general commercial and competition litigation, as well as corporate and international arbitration. He represents a wide variety of clients before courts of all levels, including the EU Court of Justice.

His practice spans a broad range of complex disputes, often involving cross-border elements, regulatory challenges, and high-value commercial claims. Sjef advises and litigates on matters such as contractual conflicts, liability issues, competition law damages, shareholder disputes, ESG topics and public procurement disputes. He is frequently engaged by multinational corporations across sectors including pharmaceuticals, financial services, energy, and industrials, and is known for his strategic approach in both urgent interim relief proceedings and long-running litigation.

Sjef has registered the following principal legal practice areas in the Netherlands Bar’s register of legal practice areas (rechtsgebiedenregister):

• General Practice, Private law (Algemene Praktijk, Burgerlijk recht)

Based on this registration, he is required to obtain ten training credits per calendar year in each registered principal legal practice area in accordance with the standards set by the Netherlands Bar.

• Represented several major industrial groups across multiple jurisdictions in follow-on damages litigation over an infringement of EU competition law.
• Defended Mitsubishi in landmark follow-on cartel damages litigation in the Netherlands.
• Represented BiosanaPharma B.V. in urgent interim relief proceedings before the Dutch court, following a contractual dispute with NASDAQ-listed Alvotech.
• Advised a multinational construction company on a complex workplace accident and related liability issues.
• Advised MSD Animal Health on its legal strategy in relation to its operations in North Africa, with a particular focus on Algeria. 
• Represented Barclays c.s. in relation to three separate proceedings initiated in the Netherlands by Stichting FX Claims. 
• Represented the portfolio companies, Papyrus Group and OptiGroup AB, of FSN Capital Partners in
  summary proceedings initiated by Divide B.V. and Impera B.V.
• Represented Almirall, a pharmaceutical company specializing in medical dermatology with a market capitalization of approximately EUR 2.4 billion, in relation to various advertisement claims.
• Advised and represented Bauer Media Outdoor in relation to a variety of issues, including in multiple public procurement disputes.

• Recognized as a Leading Associate for Dispute Resolution: Commercial Litigation by the Legal500 (2025)

• Dutch Bar Association (NOvA)
• Dutch Association for Competition Law
• Dutch Association for Corporate Litigation
• Dutch Association for Procedural Law