Arnold & Siedsma

IAM Research

The Patent 1000 focuses exclusively on patent practice and has firmly established itself as the definitive 'go-to' resource for those seeking world-class legal patent expertise.

Gold - Firms: prosecution

The Arnold & Siedsma crew is made up of judicious go-getters with the agility required to handle even the most complex cases. Its wide geographical reach only enhances its expertise, and the team delivers versatile and constructive patent strategies. In Antwerp managing partner Nele D’Halleweyn receives effusive feedback from peers and patrons alike: “Nele is one of the best patent attorneys in her field. She knows the patent procedure inside and out and has a very quick and thorough understanding of technological concepts.” “Nele is a smart strategist and unquestionably one of Belgium’s top attorneys. She grasps the concept of an invention within minutes and defends patent applications with a high success rate.” Joining her in the IAM Patent 1000 this year is Bart Laenen, a chemist who has been drafting new patents for Ghent University, a long-time client of many years.

Gold - Firms: prosecution

Arnold & Siedsma has been at the vanguard of the Dutch IP landscape for over a century, and in this time has developed into a European powerhouse with 12 offices across the Netherlands, Belgium, Germany and Switzerland. It leverages its enviable geographical reach to provide a precision prosecution service, and with seven locations around the country, its technically proficient team is always available to clients. In Eindhoven Rogier Brouwer, Bart Jacobs and Paul Hylarides have plenty of business to keep them busy. On behalf of Dredging International NV, Brouwer has been invention harvesting, delivering freedom-to-operate advice, handling opposition and court actions, and providing general IP counsel; Jacobs has been leading the team responsible for developing an international IP strategy for high-tech electronics company Ampleon; and Hylarides is the main point of contact for the likes of The Boeing Company, Fuji Seal and Illumina. Marcel van Kooij and Martin Luten are holding down the fort in IP capital The Hague. Van Kooij, a biochemistry ace, files and defends biotechnology patents for a variety of significant national and international companies, as well as innovators in the start-up community. In the automotive space, Luten is the European representative for NSK Ltd., Japan’s largest manufacturer of bearings, alongside Amsterdam-based Arjen Hooiveld – who is noted for his expertise in advising Japanese companies with their European patents. Making magic happen in Nijmegen, Petri van Someren provides commercially focused patent prosecution services in fields as varied as food and drink, medical technology, plant breeding, and chemistry. Rounding off the practice and bringing contentious firepower to the team is Michiel Rijsdijk. When he is not duking it out in court, he is negotiating contracts that effectively protect IPrights.

Firm Profile

Arnold & Siedsma is an all-round service provider for the protection of intellectual property. Since 1920, your creations have been our motivation. We have over 100 years of experience in the legal protection of intellectual property of inventions, trademarks and designs for individuals, as well as for large multinationals, in the Netherlands and abroad. In addition to our offices in the Netherlands, Germany, Belgium and Switzerland, Arnold & Siedsma has an extensive global network of agents so that we can protect your rights anywhere in the world.

Arnold & Siedsma has more than 60 in-house technical and legal experts with knowledge of all the key innovative sectors, from biotechnology and pharmaceuticals to semiconductors and software. Each client is assigned a patent attorney who specialises in the relevant, specific discipline. Our trademark and design attorneys are the best partners for all issues related to your trademarks or protecting the unique design of your products. Our IP attorneys at law can help you with anything related to legal procedures, such as enforcing your rights.

ISO 9001 certified

For the past 100 years, we have been a reliable partner for our clients with regard to all IP issues. In 2015, we became the first large Dutch IP agency with foreign offices to be ISO 9001 certified. This certification is valid for all our offices in the Netherlands and abroad. We are proud of our ISO 9001 certification because it represents what our firm stands for: say what you do, do what you say, prove it.


At Arnold & Siedsma, we believe in customised work and this can be seen in the way we operate. You can count on our personal attention, a fixed account manager and a regional office in your area.

The lines of communication with our specialists are short and personal. Service is our top priority. We stay in close touch with our clients so that we can provide you with a fast and responsive service. With offices throughout the Netherlands and Belgium, our specialists are always within proximity. At Arnold & Siedsma, you will be assigned one or two dedicated account managers. The long-term relationship ensures that they know your business and strategy, which in turn means that they will be able to give you the correct advice for your business, in line with your multi-annual planning. Your account manager will maintain regular contact with you. The protection of your innovation is of great economic value but can also be costly. This is why, at Arnold & Siedsma, we attach great importance to clear communication before, during and after each procedure.

Because we are a full-service provider, we have in-house specialists from all IP disciplines. Our patent attorneys, trademark and design attorneys and lawyers work closely together. We can pull together a team from several disciplines for our clients so that problems and issues are communicated between the different disciplines quickly, seamlessly and without unnecessary costs. Arnold & Siedsma is uniquely positioned as a service provider in the Netherlands thanks to this team-based approach.


Our patent attorneys have years of experience in supporting companies in various sectors and are therefore up to date with developments in your discipline. This technical knowledge and experience guarantee the optimisation of your rights. The main sectors in which Arnold & Siedsma is active are chemistry and pharmacy, electrical engineering and physics, mechanical engineering, biotechnology and food, and materials and software. Our experienced specialists can assist you with the protection of your intellectual property in these sectors.

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