Diederik van der Kooij

Advocaat | Counsel



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Diederik van der Kooij specialises in litigation, focusing on liability matters often related to the financial and technology sector. He has strong analytical skills due to his mathematics and computer science background and brings a deep understanding of the issues at hand, making him perfectly suited to litigate highly technical and complex matters. Diederik is involved as defense counsel in several mass claims, with a special focus on collective redress issues in his practice and as a subject of legal theory. He has wide experience as a Supreme Court lawyer and represents clients in regular cassation proceedings as well as in preliminary ruling proceedings on liability law, insurance law and consumer protection law. He has been involved in several landmark Supreme Court decisions in these areas.

Diederik received a Ph.D. from Erasmus University Rotterdam on contractual and tortious liability and authored many publications in this field.

He is a member of the Dutch Association for Procedural Law, the Dutch Association for Civil Law, the Dutch Association for Liability Law, the Dutch Association for Financial Law and the Dutch Association of Civil Cassation Lawyers.

Qualifications & Experience

  • LL.M. Dutch Law (Tilburg University)
  • LL.B. Dutch Law (Tilburg University)
  • Ph.D. Erasmus University Rotterdam
  • Advised the on the Toronto Stock Exchange listed WSP Global Inc., one of the world's leading professional services firms providing engineering and design services to clients in the Transportation & Infrastructure, Property & Buildings, Environment, Power&Energy, Resources and Industry sector as well as offering strategic advisory services, on the acquisition of multidisciplinary consultancy- and engineering firm Lievense


  • Advised Ballast Nedam on an appeal case against Max Bögl, a former joint venture partner. Ballast Nedam wins court of appeal case against Max Bögl. The Supreme Court has rejected an appeal in cassation, lodged by Max Bögl. For Ballast Nedam this ruling means an elimination of a risk of over 9 million euros, without further financial impact. Ballast Nedam brought action in 2003 against Max Bögl for breach of contract in the tendering stage of three underground stations on the North-South Line.