Diederik is a well-known competition lawyer and one of the founders and managing partners of Maverick Advocaten N.V., the leading competition law firm in the Netherlands. Diederik has an outstanding track record in the healthcare and pharmaceutical industry, the agricultural sector and the public transport sector. He has succesfully litigated on behalf of healthcare providers against healthcare insurance companies of the Dutch Healthcare Authority (NZa). He successfully challenged the abuse of an insurers’ purchasing power and assisted the branch association Dutch Mental Healthcare Association and 19 members in preliminary relief proceedings against five healthcare administration offices due to insufficient long-term care rates in 2021.

Furthermore, Diederik has extensive experience with complex merger control issues, including second phase proceedings at both the European Commission and the Netherlands Authority for Consumers and Markets. He also assisted companies during dawn raids. Diederik submitted leniency applications to these authorities besides working on cartel investigations and proceedings. He advised companies on co-operation and distribution agreements and allegations of abuse of a dominant position.

Seconded to Shell as antitrust counsel Diederik gained experience with the ins and outs of competition law in the oil and gas industry. He is a frequent speaker and contributor to journals on competition law, regularly lectures at the Grotius Acadamy and provides compliance trainings for clients in various sectors.

Before co-founding Maverick Advocaten N.V. in 2013 Diederik practiced law at De Brauw and Van Doorne.