Mr Dennis Zieren > Ploum > Rotterdam, Netherlands > Lawyer Profile

PO BOX 711

Work Department

Procurement law
IT & privacy
Technology, media and telecom


Attorney at law, partner


Dennis graduated from Leiden University and has joined Ploum in 1999. Dennis has become a partner of Ploum in 2006. Before joining Ploum Dennis has worked as an in-house lawyer for the Royal Dutch Air Force and a major Dutch insurance company.

Starting from a broad commercial contracts and commercial litigation practice, Dennis has developed since 2000 an expertise in first IT & Privacy Law and later on Public and Utilities Procurement Law.

Dennis has a large knowledge and experience in drafting, reviewing and negotiating all kind of IT contracts on behalf of serviceproviders as well as on behalf of customers. Dennis also often litigates in IT-disputes in the Dutch courts and (IT) arbitration tribunals. Dennis is amongst others an active member of the Platform Outsourcing Netherlands (PON).


  • ITechlaw
  • Nederlandse Vereniging voor Aanbestedingsrecht (NVvA), the Dutch Association for Procurement Law
  • Nederlandse Vereniging voor Informaticatechnologie en Recht (NVvIR), the Dutch Association for Information Technology and Law
  • Vereniging Privacy Recht (VPR), the Dutch Association for Privacy Law
  • Vereniging Informaticarecht Advocaten (VIRA), the Dutch Association for Information Technology Law


Dennis graduated from Leiden University.Dennis has completed two Grotius specialisation programmes: Information Technology Law in 2002 and European and Dutch Procurement Law in 2009.

Lawyer Rankings

Netherlands > Data privacy and data protection

Ploum is sought-out by clients for its expertise in e-health data protection matters, regularly advising and assisting life sciences and health care companies with a slew of data and cybersecurity issues. The team is also adept at advising on marketing and e-commerce sectors, including issues relating to processing employee data and international data transfers. The privacy team is co-headed by Dennis Zieren and Dorine ten Brink who are well-versed in issues that span IT and data privacy including contracts and data transfers. Nina Witt is also noted for her knowledge on privacy in the health care sector.