header image: picture of connected dots


portrait photo

Willem Hoyng Attorney, Partner

Office location
Telephone number
+31 20 592 4415

French, English, Dutch, German
Copyright, Designs, Patents, Supreme Court Litigation, Trademarks
University of Tilburg, Ph.D., 1988
King's College, English Law, 1976
Admitted to the Bar, 1973
University of Leiden, 1971

Willem is the managing partner of Hoyng Monegier LLP. Willem’s practice primarily consists of litigating in the field of intellectual property law. Willem acts before all the national courts (the courts of first instance, the courts of appeal and the Supreme Court). He also regularly litigates before the Court of Justice of the European Union (CJEU) and the European Patent Office (EPO). Willem is also involved in advising on European patent strategies and coordinating and conducting European patent proceedings. He is the adviser of many innovative Dutch and foreign multinationals, including pharmaceutical and biotechnological companies.

Willem is a member of a select group of lawyers admitted to appear before the Dutch Supreme Court. Indeed, he handled his first supreme court case in 1973. Willem's track record for IP litigation before the Netherlands' highest court is unsurpassed. Noteworthy cases include:

Droste – Tjoklat HR 2 March 1990
Vredo – Veenhuis HR 4 June 1993, NJ 1993, 659
Hupkens – Van Ginneken HR 27 December 1994
BAT – Doucal HR 16 April 1999
Van Bentum - Kool HR 29 March 2002
Roche – Primus HR 19 December 2003
Philips – Postech HR 19 March 2004
Souza Cruz – Tabacalera HR 17 February 2006
Stork – Bakels HR 29 September 2006
Dijkstra – Saier HR 22 December 2006
Lego – Mega Brands HR 20 November 2009

Willem is a professor of Intellectual Property Law at the University of Tilburg. He has written numerous publications in the field of intellectual property law. In 2002, Willem received the Wim Mak award for his article on the use of market research in legal actions involving trademark law.


  • Monsanto v Cefetra. Represented Monsanto in the first patent case (interpretation of the Biotech Directive) before the CJEU.
  • Isover St Gobain v Rockwool. Represented Isover St. Gobain in a patent infringement case lasting 25 years. The Supreme Court confirmed that Rockwool’s patent was invalid and not infringed.
  • Dijkstra v Saier. Represented Dijkstra before the Dutch Supreme Court, which accepted the doctrine of file wrapper estoppel in Dutch patent law. Convinced the Supreme Court to revoke the decision of the Court of Appeal.
  • Van Bentum v Kool. Represented Van Bentum before the Dutch Supreme Court, convincing the court that foreseeable equivalents which the patentee did not claim can still be claimed under the doctrine of equivalents.
  • Mega Brands v Lego. Convinced the Court of Appeal of Den Bosch that, contrary to the earlier decision of the Court of Appeal of Amsterdam, the sale of copies of Lego bricks by Mega Brands should not be prevented under the doctrine of slavish imitation and thereafter convinced the Supreme Court to dismiss Lego’s appeal.
  • Solvay v Honeywell. Argued that Dutch courts can grant cross border injunctions in preliminary injunction proceeding. The ECJ agreed.


  • European Patent Lawyers Association (EPLAW), Former President
  • International Association for the Protection of Intellectual Property (AIPPI), Former President of the Dutch Group
  • IP Advisory Committee of the Dutch Bar, Chairman
  • Former member of the Government Advisory Committee on patents
  • Reappointment as one of the four members of the Supervisory Board of the Academy of the European Patent Organisation


  • 100 years of the Patent Act in the land of the Polders, A Century of Patents in the Netherlands
  • Patent Law and the Dutch Supreme Court, Festschrift (2010) De Gryse
  • Contributory Infringement, Festschrift Brinkhof
  • Een pleidooi voor enige demassificatie in het Octrooirecht, 200 jaar Iustitia & Amicitia
  • De Angorakat, Festschrift Spoor


  • TLI Symposium, Nijmegen, March 2012
  • BIE Symposium “innovation 2.012”, April 2012
  • POLIS Symposium “Innovation and Imitation”, Tilburg, April 2012
  • CIPA, Dutch patents case law (webinar), May 2012
  • Patent congress Amsterdam (Kluwer), June 2012
  • AIPPI NL, Rijswijk, “Rules of Procedures of the future Patent Court”, September 2012
  • Merken- en Modellendag (Chairman), October 2012
  • CPO, “the do’s and don’ts in patent prosecution with an eye on litigation”, Utrecht, October 2012
  • CIPA “the future Union Patent”, London, October 2012
  • UNION congress “Enforcement strategies in the EU”, Amsterdam, November 2012
  • IP Summit (chairman session “Unified Patent Court”), Brussels, December 2012
  • Leidse IE Alumni, speaker on the subject Unified Patent, University Leiden, 26 September 2013
  • Speaker at New York State Bar Association IP Section Fall Meeting on the subject European Unitary Patent and Unified Patent Court, Lake George, New York, USA, 19 October 2013
  • Seminar of the German Patentanwaltskammer, speaker on the subject Rules of Procedure of the Unified Patent Court, Munich, 19 November 2013


  • “An experienced trial lawyer who projects amazing authority in the courtroom”, IAM Patent 1000 2015
  • Sources are quick to applaud Willem Hoyng as "really in a different class. He is an extremely strong litigator who immediately drills down to the issue and familiarises himself quickly with all aspects of the case." He has a broad practice and is widely regarded as one of the best patent litigators on the market. Chambers Global 2015
  • Willem Hoyng is first and foremost a patent litigator, but “his trademark knowledge is at the highest level” World Trademark Review 2015
  • “The crowned king of patent litigation”, Willem Hoyng “is the best of the best – there is nobody else who does what he does. He is very convincing, whether he is talking to someone in the pub or before the bench. He is an inspiring lawyer” IAM Patent 1000
  • "very strong in tactics and strategy" Legal 500 2014
  • “"absolutely stellar" and "one of the best patent litigators in Europe." He is able to plead before the Supreme Court and is valued by clients for his "presence and impact in the courtroom." “ Chambers Global 2014
  • Willem Hoyng is one of the most influential, and peers suggest that “he may be the best patent litigator we have in the Netherlands”, IAM Patent 1000 2013
  • “He is outstanding on the big-picture strategy and has real credibility when presenting a case”, Chambers Global 2013
  • "Maybe the greatest litigator there has ever been in the Netherlands", World Trademark Review 2013
  • “Willem Hoyng enjoys an undisputed reputation as the top patent lawyer in the Netherlands.” Chambers 2012
  • “His superb track record in litigation has earned him a spectacular reputation on the market” IAM Patents 1000 2012
  • “Star lawyer Willem Hoyng is praised as ‘a brilliant IP practitioner’" Chambers 2011
  • [Willem] “is a ‘high-class IP lawyer’, with the ability to ‘grasp technology matters quickly and make them easier to understand for the court’”. Legal 500 2010
  • [Willem] “is a top patent litigator, commentators agree.” He gives his clients the confidence that everything will be fine," they said. He also litigates in trade mark and design cases, as well as offering clients strategic advice”. Chambers 2010