French civil procedure relies heavily on court-appointed experts to clarify complex technical matters. In intellectual property disputes (trademarks, patents, designs, software, copyright), the judicial expert plays a central role in qualifying infringement and quantifying damages. Nathalie Dreyfus has been a court-appointed IP expert at the Paris Court of Appeal since 2009 and at the French Court of Cassation since December 2022.
Reviewed by Nathalie Dreyfus, European Trademark and Patent Attorney, court-appointed IP expert at the Paris Court of Appeal and the French Court of Cassation. Last updated: June 2026.
Court-appointed experts in France act under Articles 232 to 284 of the French Code of Civil Procedure. They are sworn, neutral and independent, and they deliver a written report that is submitted to the parties for adversarial discussion before being filed with the court.
In IP disputes, the expert is regularly asked to address three sets of questions. Is the contested object technically equivalent to the protected one (claim construction, similarity analysis, technical infringement)? Has the contested object been derived from the protected one (originality, prior art, technical genealogy)? What is the proper amount of damages, taking into account lost profits, unjust enrichment of the infringer, moral prejudice and reputational harm?
The court-appointed expert can also be retained privately by a party, before or during litigation, to deliver a technical opinion or to anticipate an opposing party’s claims (private expertise, expertise officieuse). The opinion carries weight when the expert is also a court-listed expert.
Nathalie Dreyfus has been a court-appointed IP expert at the Paris Court of Appeal since 2009, specialising in industrial property and in particular trademarks.
Source: Cour d’appel de Paris, official list of judicial experts.
Nathalie Dreyfus was appointed as a court-listed expert at the French Court of Cassation in December 2022, joining an exclusive list of national experts called upon by the supreme civil court.
Source: Cour de cassation, official list of judicial experts.
Articles 232 to 284 of the French Code of Civil Procedure (Code de procédure civile) set out the framework for judicial expertise: appointment, mission, adversarial principle, report filing and judicial control.
Source: French Code of Civil Procedure, Articles 232 and following.
Article L.331-1-3 of the French Intellectual Property Code sets the rules for damage assessment in IP infringement: lost profits, infringer’s unjust enrichment, moral prejudice. The expert’s calculation is a key element of the court’s decision.
Source: Article L.331-1-3 of the French Intellectual Property Code.
Six typical scenarios justify involving a court-appointed IP expert.
On a judge’s order or by private retainer. The expert checks independence, conflicts and capacity, then accepts the mission in writing.
Document review, technical inspections, hearings of parties and witnesses, requests for additional information. The adversarial principle (contradictoire) is respected throughout.
A pre-report (pré-rapport) is shared with the parties for observations and comments. Parties have a fair opportunity to challenge the expert’s preliminary findings.
The final report is filed with the court, summarising the methodology, evidence, expert reasoning and conclusions on the questions raised in the mission.
If summoned by the judge, the expert can be heard at trial to clarify the report. The report itself remains a key piece of evidence subject to judicial assessment.
Listed at the Paris Court of Appeal since 2009 and at the French Court of Cassation since 2022.
European Trademark and Patent Attorney, founder of Dreyfus & Associés, with twenty years of practice.
Routinely appointed on disputes involving US, UK, German, Indian and Chinese parties.
Technical and economic skills to quantify damages under Article L.331-1-3 of the French Intellectual Property Code.
Conflict-of-interest checks applied at appointment, no representation of parties in the dispute.
Adversarial method, structured analysis, clear conclusions, recognised by French courts as reliable.
Court-appointed expertise is ordered by a judge in pending proceedings and follows the strict procedural framework of Articles 232 and following of the Code of Civil Procedure. Its report has strong evidentiary weight.
Private expertise (expertise officieuse) is commissioned by a party, typically before or alongside proceedings, to assess a claim, prepare a pre-litigation strategy or feed an out-of-court negotiation. The report is admissible in court but is treated as a party document, not as a neutral expert opinion. When the private expert is also a court-listed expert, the report carries significantly more persuasive weight.
A neutral and independent technical expert appointed by a judge to clarify the technical aspects of an intellectual property case. The expert acts under Articles 232 and following of the French Code of Civil Procedure, respects the adversarial principle and files a written report subject to judicial control.
She intervenes primarily in industrial property, with a strong specialisation in trademarks, but also patents, designs, copyrights and domain name disputes. She has handled cross-border disputes involving the US, UK, Germany, India and China.
In pending proceedings, your counsel can request the appointment in the writ or by motion during the case. The judge then selects the expert from official court lists. For private expertise, parties can directly retain the expert under a written engagement letter.
The expert is not a witness, but the judge can summon the expert to the hearing to clarify the report. The expert’s role remains neutral, independent and limited to the questions raised in the mission.
Yes. A French court-appointed IP expert can deliver an opinion that is filed in a foreign proceeding (US discovery, UK High Court, Indian or Chinese courts) to certify French IP rights, French market practice or French damages calculation methodology.
In court-appointed missions, the judge orders a provisional advance (consignation) to be paid by the requesting party, with final fees set at the end of the mission. In private expertise, fees are governed by the engagement letter signed with the parties.
