Within our chemistry team, which he co-leads, Gwennhaël advises numerous French and international clients with all patent-related matters, from drafting to prosecuting both domestic and foreign patent applications. He also provides freedom to operate opinions and conducts patent validity assessments.

Gwennhaël has gained substantial experience in proceedings before the European Patent Office (EPO), and frequently represents his clients in opposition and appeal proceedings.

He also has experience of patent litigation and represents clients in litigation before the Unified Patent Court (UPC).

Gwennhaël has been practicing for over 20 years in the fields of organic chemistry, cosmetics, dermatology, pharmacy, polymer and materials chemistry and physics of materials,electrochemistry, metallurgy, and environmental chemistry.

He advises a wide range of clients, from French, European, and international SMEs to multinational corporations, as well as start-ups, universities, and innovative laboratories.
After graduating as a Chemical Engineer from the Ecole Européenne de Chimie, Polymères et Matériaux (ECPM) in Strasbourg – where he completed a scientific curriculum taught in French, English, and German – and gaining professional experience in the Netherlands and Germany, Gwennhaël began his career with CASALONGA in 2004. He became a partner in 2015.

Adjunct teaching / Professional organizations

Gwennhaël is an active member of the Examination Committee for the European qualifying examination (EQE).

He is a member of the French Patent and Trademark association (Compagnie Nationale des Conseils en Propriété Industrielle – CNCPI) of which he co-chairs the UP & UPC committee. He participates in the Dispute Resolution Committee of the Licensing Executives Society France (LES France) and in the IP Practice in Europe Committee of the American Intellectual Property Law Association (AIPLA).
Within the European Patent Institute (epi), he has been elected as a substitute member of the Litigation Committee (LitCom), which considers and discusses all aspects of patent litigation in Europe, in particular on infringement and validity of European Patents, and plays an active role in monitoring, discussing and preparing epi positions on matters concerning the Unitary Patent (UP) and the Unified Patent Court (UPC) system.

Latest publications

• - December 2022 : « A new patent for Europe » avec Julien Thon – published in Le Figaro, on 6^th December 2022. For more information, see under this link

Latest interventions

• - April 2023 : Presentation of a comparison of the two systems for invalidating a patent in Europe (opposition before the EPO and action for revocation before the UPC) in order to show the advantages and disadvantages of each system - "IP Practice in Europe" committee of the AIPLA (American Intellectual Property Law Association)

• - June 2022 : Workshop on "How to adapt my company’s strategy to JUB-related risks" – webinar entitled “Companies, ready or not ready for the UPC ?” organized by the Dispute Resolution Committee of LES France (Licensing Executives Society France)

• - March 2022 : Interview on the future European patent system – LexInside (Décideurs TV). Find the program under this link

Education

• - Master’s degree in Intellectual property Law, specialization in Industrial property, at CEIPI (Strasbourg University) – 2019
• - Postgraduate Diploma in Industrial Property Law at CEIPI (Strasbourg University) – 2004
• - Graduate degree in Chemical Engineering of Ecole Européenne de Chimie, Polymères et Matériaux (ECPM, Strasbourg) – 2003

Languages

French, English, German

Latest awards

• - Leaders League :
• Leading in Intellectual property – Patents (general) 2025
• Leading in Healthcare, pharmaceuticals & biotech – Chemistry, biotech, and life sciences patents 2025

• - Legal 500 : Recommended lawyer 2025

• - IAM Patent 1000 : Bronze - Individuals : prosecution in 2025.