Oyat avocats Paris - Marie-Hélène Tonnellier

Marie-Hélène Tonnelier

Founding Partner · Digital/IP

Oyat avocats Paris - Marie-Hélène Tonnellier

Member of the Paris Bar since 1990, Marie-Hélène co-founded Oyat in 2022.

Marie-Hélène began her career in London within a solicitors’ firm prior to joining Moquet Borde & Associés (Paul Hastings) in 1990, then Jeantet in 1995. Then she has been a partner for 22 years at Latournerie Wolfrom Avocats where she created the digital and intellectual property department.

Marie-Hélène is one of the leading lawyers in the digital world. She advises and litigates on all issues related to IT projects, innovations (AI, robots, etc.), e-commerce and personal data. She also intervenes in media law and intellectual property.

Highly skilled in the sectors of distribution, tourism, luxury, new economy, mobility, media or services, she assists her clients in the implementation of strategic projects or in their digital transformation, helps them navigate through the various new rules in these various fields, assists them in often complex and innovative litigations.

Her oyat is between the Garde Guérin and petite Salinette beach: her breton paradise!


  • University of Panthéon-Sorbonne Paris I – Post graduate degree (DEA) in Business Law
  • University of Panthéon-Assas Paris II – Post graduate degree (DESS) of Notary Law
  • University of Panthéon-Sorbonne Paris I – Master’s Degree Droit des affaires


French, English


  • Lecturer at the University Paris XI-Saclay, Master Intellectual Property and Digital Law
  • Lecturer at the HEAD school, Master Digital and Intellectual Property Law
  • Former President of the IFCLA
  • Member of the Board of Directors of AFDIT
  • Member of the International Bar Association (IBA)