Jean-Sébastien MARIEZ > Momentum Avocats > Paris, France > Lawyer Profile

Momentum Avocats
11 Avenue Delcassé


Partner – For the past 15 years, Jean-Sébastien has helped players in the digital economy by protecting their innovation (software, databases, artificial intelligence, e-commerce platforms), securing their business activities (personal data, cybercrime, e-reputation) and providing representation in litigation before civil, commercial and criminal courts (piracy, unfair competition, Internet) and supervisory authorities.

His practice focuses on ICT service activities, Media, Gaming, Luxury and Consumer goods.

Jean-Sébastien also advises on public and regulatory affairs in order to facilitate early awareness and integration of significant regulatory changes impacting the activity of his clients. In this capacity, he has been active recently in the context of the adoption of the French “Hate speech Act”, “Fake news Act” as well as the transposition of European Directives and Regulations.


Before founding Momentum Avocats, Jean-Sébastien worked as a partner in the law firm De Gaulle Fleurance & Associés, which he joined after practicing in-house at Microsoft where he served as Head of the Cybersecurity and Anti-Piracy division of the French Legal & Corporate Affairs Department.

Jean-Sébastien was involved for ten years with the association Avocats Sans Frontières, where he actively contributed to the raising of European funds, the management of mass litigation programs relating to the violation of human rights and the release of convicted women at the end of proceedings initiated before the ECOWAS Court.


French, English





2005 – Paris Bar Admission

2001 – Master of Laws (LL.M.) in European Business Law – Université Nancy II

2002 – DESS post-graduate degree in Politics and International Relations – Université Paris XI

Lawyer Rankings

France > Intellectual property: Trade marks and designs

Momentum Avocats was created in September 2020 by Julien Canlorbe (formerly at Meridian), Jean-Sébastien Mariez and Julie Carel (both formerly at De Gaulle Fleurance & Associés). The young independent firm has already made name for itself in the market, notably for its high-profile litigation practice. The advisory work on the structuring of IP portfolios and their valuing in the context of audits or commercial contracts also deserves a mention. The luxury goods, fashion and publishing sectors are mainstays of the firm, but the team offers wide-ranging sector expertise. Companies from the digital economy, including e-commerce platforms and artificial intelligence players, also turn to the firm for strategic advice.

France > Intellectual property: Copyright

Momentum Avocats opened its doors in September 2020 when practice heads Julien Canlorbe, formerly at Meridian, Julie Carel and Jean-Sébastien Mariez, former practitioners at De Gaulle Fleurance & Associés, joined forces to assist art institutions, tech companies, digital platforms and brands with IP and IT issues. Equipped to handle both litigious and non-contentious work, the boutique is particularly active in the publishing, software, luxury goods, gaming and internet sectors, where it advises on pre-litigation and court proceedings as well as on the negotiation and drafting of agreements.

France > Industry focus: IT and internet 

(Next Generation Partners)

Jean-Sébastien Mariez – Momentum Avocats

Paris > Propriété intellectuelle > Droits d’auteur

Momentum Avocats a été lancé en septembre 2020 par  Julien Canlorbe (ex Meridian ), ainsi que Julie Carel et Jean-Sébastien Mariez, deux anciens membres de De Gaulle Fleurance & Associés, Le trio accompagne des institutions artistiques, des entreprises technologiques, des plateformes numériques et des marques dans la gestion de leurs problématiques de PI/T. La boutique traite des dossiers en conseil et en contentieux. Elle est particulièrement active dans les secteurs de l’édition, du logiciel, du luxe, des jeux et de l’internet.

Paris > Propriété intellectuelle > Marques, dessins et modèles

Momentum Avocats a été créé en septembre 2020 par  Julien Canlorbe (ex Meridian) et par Jean-Sébastien Mariez et Julie Carel (deux ex-membres de De Gaulle Fleurance & Associés).  La jeune boutique jouit déjà d’une solide réputation, notamment au contentieux. Le champ d’expertises couvre aussi la structuration des portefeuilles de droits et leur valorisation lors d’audits ou de la négociation de contrats commerciaux. Le cabinet dispose d’une forte présence dans les secteurs du luxe, de la mode et de l’édition. Des sociétés du monde digital, dont des plateformes d’e-commerce et des développeurs de solutions d’intelligence artificielle, font également appel au cabinet.