Fabian Leimgruber

Senior Partner at ThomannFischer
Ranked in Switzerland
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.

Recommended - Individuals: prosecution

Commercial law outfit ThomannFischer is a premier destination for wall-to-wall IP support, thanks to its A-to-Z prosecution, litigation and transactional offering. In the words of one client: “They fulfil their brief to the highest possible standard. They quickly derive the central points of the invention at hand and skilfully implement any comments to finalise the work product in short turnaround times.” Department captain Fabian Leimgruber has a pristine track record at the EPO: “His deep legal and technical understanding of emerging technologies fills clients with comfort; he has rightfully earned his reputation as a first-rate prosecutor.”

Fabian Leimgruber's Profile

Fabian Leimgruber is a senior partner and head of ThomannFischer’s IP prosecution and litigation team. He is a registered European and Swiss patent attorney and admitted lawyer before the Swiss Federal Patent Court. He has over 20 years’ experience helping leading international companies build up their IP portfolios and resolve their IP and technology-focused disputes before trial and appellate courts, domestic and international arbitration tribunals and the European Patent Office (EPO).

Dr Leimgruber holds an LLM and a JD, and a PhD in physics. His particular area of expertise is implementing and leading international and national patent infringement litigation and nullity actions, handling complex cases before all the Swiss and German courts and the EPO. He and his team have run several large cases involving patents and standards. He has a substantial track record in EPO opposition and appeal actions, and in national nullity and infringement proceedings. In particular, he was involved in several cases that led to key decisions of the EPO Board of Appeal relating the patentability of emerging technologies.

Besides his procedural work, Dr Leimgruber maintains a large patent prosecution portfolio for international and national clients. He has many years’ experience in various large law firms in Bern, Basel and Zurich, with a focus on mobile communication and information technology, emerging technologies, nanotechnology, business methods and software patenting – particularly in the emerging field of insurance and financial technology patenting, as well as simulation technology, big data and the Internet of Things.

Dr Leimgruber provides strategic advice and expertise (IP due diligence, tax-related matters) and represents clients in European and Swiss arbitration and Asia Pacific cases. His long-term experience in Singapore and Shanghai gives him a deep insight into the particularities of various Asian legal systems.

As an author and speaker, Dr Leimgruber has recently addressed topics such as reverse payment agreements, developments in software and business model patenting (Europe, the United States and Asia-Pacific), emerging technologies, artificial intelligence and antitrust issues.

Firm Profile

ThomannFischer is a leading commercial law boutique firm for all IP and business sectors relating to technology, with a strong emphasis on IP, technology, pharma and media law. Founded in 1998, the firm provides reliable support on all aspects of commercial, IP and IT law to national and international clients. One of the firm’s defining characteristics is its commitment to the highest level of quality and client service. All of the firm’s partners have a long history of professional experience and comprehensive knowledge in their areas of practice, combining exceptional legal expertise across all business sectors where technology, commercial and legal considerations are key.

The firm’s affinity to IP and IT law is enhanced by its location in Basel, home to Switzerland’s life sciences cluster, which hosts international events such as ART Basel and the Baselworld Watch and Jewellery Fair.

Practice areas

The firm provides comprehensive expertise in litigation, IP prosecution and client counselling work across all fields of IP, IT and commercial law. This includes advising on patents encompassing numerous technologies, as well as on all aspects of trademarks, domain names, copyright, design rights, unfair competition, confidential information and related areas. The firm’s patent practice focuses on telecoms, insurance and banking technologies, life sciences, bio and nanotechnology, computer-supported inventions, data transfers, business model and services patenting, and covering all fields of the emerging technologies and industry 4.0. ThomannFischer has considerable experience in drafting and negotiating licences and other commercial IP agreements, as well as offering IP due diligence services. The firm regularly advises clients on the worldwide strategic development and management of their IP portfolios.

Our approach

ThomannFischer is one of the rare law firms that has a combination of highly experienced attorneys at law and patent attorneys working in the same firm. This makes ThomannFischer a one-stop shop for all IP-related matters, including drafting, filing, prosecuting, enforcing, litigating and arbitrating patent, trademark and design rights in Switzerland, Europe and the rest of the world.

Specifically, ThomannFischer operates one of the broadest patent prosecution practices in Europe. The firm’s patent attorneys offer a unique combination of technical and legal expertise and are trained in various technical and legal disciplines.

ThomannFischer has earned a reputation for being both tenacious and flexible before the EPO, WIPO and the Swiss Federal Institute of Intellectual Property. The firm provides the best possible protection, while always keeping clients’ business objectives and needs in mind. It is also known for being able to provide efficient IP protection in border areas of patentability as business model and services protection to emerging technological fields.

In terms of IP litigation, ThomannFischer’s experienced and skilled litigators are known for achieving outstanding results in a cost-efficient manner – something which can be achieved only through the firm’s unique combination of experienced attorneys at law and patent attorneys. ThomannFischer pursues national and international litigation strategies that deliver desired outcomes while focusing on the key elements of the litigation in order to provide positive results. ThomannFischer’s efficient approach to litigation helps to avoid expensive and wasteful approaches and ensure the best possible outcome.

ThomannFischer represents clients before all Swiss courts and authorities and the EPO. The firm’s experience also covers alternative dispute resolution, including mediation and international arbitration.

International reach

Where a client’s assignment has international dimensions, ThomannFischer liaises with many renowned IP law firms throughout the world. The firm’s expertise and experience enable it to coordinate complex transactions and successfully guide clients through multinational litigation.


Each of the firm’s professionals works in at least English, German, French, Italian and Russian.

Get unlimited access to all IAM content