13.4.2 Action for patent annulment
In contrast to infringement proceedings, which may be brought from the time of publication of the patent application or the communication of this application to the defendant, patent annulment proceedings may only be brought after the title has been granted.
13.4.2.1 Interest in taking legal action
Interest in taking legal action to annul a patent is assessed in accordance with the provisions of Article 31 of the CCP, which states that action may be brought by anyone with a legitimate interest in the success or rejection of a claim, except in cases where the law grants the right to take action only to persons qualified by law to pursue or contest a claim, or to defend a specific interest.
An economic operator has a legitimate interest in requesting the annulment of an industrial property title when, as the producer of products similar to those covered by the patent, their application is intended to remove an obstacle to the use of the technique for the requirements of their economic activity.242
The party requesting annulment does not have to demonstrate the existence of serious and effective plans to use a product implementing the patented technology (which is the condition for the admissibility of an action for a declaration of non-infringement provided for in Article L. 615-9 of the IPC – see the following section).
13.4.2.2 Grounds for annulment
According to Article L. 613-25 of the IPC, a French patent is declared null and void by a judicial decision: (a) if its object is not patentable under the terms of Articles L. 611-10, L. 611-11 (novelty) and L. 611-13 (inventive step) to L. 611-19 of the IPC; (b) if it does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art; (c) if its subject matter extends beyond the content of the application as filed or, when the patent was granted on the basis of a divisional application, if its subject matter extends beyond the content of the initial application as filed; or (d) if, after limitation or opposition, the scope of protection conferred by the patent has been extended.
Under Article L. 614-12 of the IPC, a European patent is declared null and void in France by judicial decision for any of the grounds mentioned in Article 138(1) of the EPC. According to the Convention, a European patent may be revoked with effect for a Contracting State only on the grounds that: (a) the subject matter of the European patent is not patentable under Articles 52 to 57 of the EPC; (b) the European patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art; (c) the subject matter of the European patent extends beyond the content of the application as filed or, if the patent was granted on a divisional application or on a new application filed under Article 61 of the EPC, beyond the content of the earlier application as filed; (d) the protection conferred by the European patent has been extended; or (e) the proprietor of the European patent is not entitled thereto under Article 60(1) of the EPC.
The grounds for annulment of a patent are listed exhaustively, with a lack of entitlement not considered a ground for annulment of a French patent. Furthermore, the provisions of Article 138(1)(e) of the EPC, on annulment owing to the patent holder’s lack of entitlement, are interpreted as intended to protect the private interests of the true patent holder or their successor in title so that their violation is punished by relative nullity, which can only be invoked by the injured parties and not by a competitor.243
13.4.2.3 Absence of patentability
The concept of an invention is not subject to any positive legal definition. However, the IPC specifies that a patent can be granted for inventions “in all fields of technology” (Article L. 611-10(1) of the IPC), that the descriptive part of the patent must include a statement enabling “understanding of the technical problem as well as the solution provided” (Article R. 612-12(3)) and that “the claims define the subject matter for which protection is requested by indicating the technical features of the invention” (Article R. 612-16). The invention must also be considered a technical contribution to a technical problem.
The most common type of dispute concerns the patentability of computer-implemented inventions. French case law is still guided by the criterion for contribution to the prior art in a field that is not excluded from patentability.
The IPC also excludes mere presentations of information from protection (Article L. 611-10(2)), so that an invention on new ways of displaying an aircraft’s route, without claiming any technical means related to the display method and merely describing what the pilot sees, is not patentable.244
While parts of the human body are not patentable, it is possible for “the technical application of a function of a part of the human body” to be protected by patent (Article L. 611-18).
13.4.2.3.1 Assessing the validity of priority
Under Article 4(A) of the Paris Convention, any person who has duly filed an application for a patent, in one of the countries of the Union, or his successor in title, shall enjoy, for the purpose of filing in the other countries, a right of priority during the periods hereinafter fixed; and any filing that is equivalent to a regular national filing under the domestic legislation of any country of the Union or under bilateral or multilateral treaties concluded between countries of the Union shall be recognized as giving rise to the right of priority.
Determination of the successor in title is a matter for the applicable national legislation on the transfer of rights,245 which is not aligned with the solution adopted by the EPO.246
In French law, the transfer of the priority right must be done in writing247 and may not arise from a general statement.248
Under Article 4(H) of the Paris Convention, “priority may not be refused on the ground that certain elements of the invention for which priority is claimed do not appear among the claims formulated in the application in the country of origin, provided that the application documents as a whole specifically disclose such elements.”
French courts, like the EPO Enlarged Board of Appeal,249 generally apply the “gold standard” to assess the criteria of the same invention. The conceptual breakdown of a claim250 has not yet been the subject of a specific decision from French courts.
13.4.2.3.2 Absence of novelty
According to both Article L. 611-11 of the IPC and Article 54 of the EPC, an invention shall be considered to be new if it does not form part of the prior art, with the prior art comprising everything made available to the public by means of a written or oral description, by use, or in any other way, before the date of filing of the patent application.
To be included in the state of the art and be lacking in novelty, the invention must be found in its entirety in a single, undisputed prior art reference, with the elements that constitute it in the same form and the same arrangement, with the same functioning to produce the same technical result.251 Case law then refers to the “complete” prior art.252
The fact that a prior art reference may be complete, including when it only implicitly discloses certain features, is admitted by judges on the merits.253
In contrast to EPO practice (EPC Guidelines, F-IV, 4.13.1), indicating a purpose in a product claim confers novelty on this claim, even when there is a prior art suitable or appropriate for that purpose.254
13.4.2.3.3 Absence of inventive step
Under Article L. 611-14 of the IPC, which was drafted to be identical to Article 56 of the EPC, an invention shall be considered as involving an inventive step if, having regard to the prior art, it is not obvious to a person skilled in the art.
In this respect, judges may apply the problem-solution approach255 developed by the European Patent Office if they consider it relevant, but this method of assessment is not mandatory.256
The term “obvious” refers to that which follows logically from the prior art and does not assume any specific skill beyond combining elements reasonably accessible to a person skilled in the art.257
13.4.2.3.3.1 Definition of a person skilled in the art
As an essential stage of the inventive step assessment, the Court of Cassation confirms that judges have defined the person skilled in the art.258 Their art is the technical area relevant to the problem that the invention, the subject matter of the patent, proposes to solve.259 This person has standard knowledge of the relevant field and is able, through their professional skills alone, to develop the solution to the problem that the invention proposes to solve.260 The person skilled in the art may not consult a specialist in another field261 and may not refer to documents from a field other than their own.262 In contrast, they may consult documents in related fields, if prompted to do so because the problem to be solved also arises there.263 If that is the case in the technical field in question, the person skilled in the art may also consist of a multidisciplinary team.264 In France, the person skilled in the art is defined in accordance with their technical skills and not only by reference to their level of qualification.
13.4.2.3.3.2 Means of assessing the patent's contribution to the prior art
The starting point for assessing the contribution to the prior art is the person skilled in the art.
The person skilled in the art is considered to be “encouraged” (in principle) to consult patents in the same field that address the same technical problem. The same applies to similar technical fields265 or general documentation when the technical problem is posed in the same terms. The encouragement to combine prior art documents is thus technical, but it may also be commercial (the person skilled in the art may, for example, be encouraged to suggest to clients an electrical outlet that works without an adapter). In contrast, the person skilled in the art cannot be considered to be encouraged to combine documents from different technical fields or intended to solve different technical problems.266 Encouraging the person skilled in the art to combine a prior art document or documents with their general knowledge appears to be a more flexible approach than that developed by the EPO. However, the Court of Cassation confirms that the judges have not engaged in ex post reasoning.267
Under French case law, a patent is not considered valid when, in the opinion of the person skilled in the art, it would not make any contribution to the prior art or enable its applicant to pursue a field of research that has not yet yielded concrete technical results. An invention must therefore have a “credible” or “plausible” technical impact at the time of filing, and the absence of such an impact is penalized on the grounds of a lack of inventive step.268 The credible nature of the technical impact is assessed at the date of priority or of filing,269 in view of the elements contained in the application, including the disclosures of the patentee, who is not required to provide in the application the results of tests or trials or any other data.270 Patentees are entitled to demonstrate, through evidence existing at the time of filing, that they have been in possession of the invention since that time, provided, of course, that the person skilled in the art can deduce what the invention and the technical impact claimed consist of, from the patent alone, on the basis of common general knowledge.271 Evidence subsequent to the filing may also be taken into consideration, but it may not be the sole basis for demonstrating the credibility of the technical impact.272
It is incumbent on the party applying for annulment of a patent to provide proof of the prior art (or the general knowledge of the person skilled in the art) on which it relies to secure its annulment; the prior art cannot be based merely on disclosures,273 but must be supported by documentary evidence or testimony.
13.4.2.3.4 Lack of industrial application
Only an invention with a possible industrial application is patentable (Article L. 611-10 of the IPC), i.e., if its subject matter can be manufactured or used in any type of industry, including agriculture (Articles L. 611-15 of the IPC and 57 of the EPC), with “industry” referring to all types of technical activity.
13.4.2.3.5 Insufficient disclosure
An invention is considered sufficiently disclosed when the person skilled in the art, through reading the description and through their normal professional, theoretical and practical knowledge, is able to reproduce the invention. Moreover, if some elements essential to the functioning of the invention are not explicitly included either in the text of the claims or in the description, or in the drawings of the invention claimed, it does not necessarily mean that the invention has not been disclosed in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art.274
When a claim concerns a subsequent therapeutic application of a substance or composition, obtaining this therapeutic effect is a functional technical feature of the claim; as a result, while it is not necessary to demonstrate this therapeutic effect clinically to satisfy the requirement for sufficient disclosure, the patent application must nonetheless directly and unambiguously reflect the therapeutic application claimed so that the person skilled in the art understands, on the basis of commonly accepted models, that the results reflect this therapeutic application.275
In contrast to most EPO case law, French courts do not necessarily require the invention to be capable of being implemented across the entire scope of the claim: a single example can be enough to demonstrate that the invention has been sufficiently disclosed. In other words, insufficient disclosure requires it to be demonstrated “that it is impossible for the person skilled in the art to reproduce the invention and implement it from reading the description, claims and drawings [...]”276 The Court of Cassation has not yet ruled on this issue.
13.4.2.4 Annulment arising from modifications
13.4.2.4.1 Extension beyond the subject matter of the application
Under Article L. 613-25(c) of the IPC and Article 123(2) of the EPC, a patent shall be declared null and void by judicial decision [...] when its subject matter extends beyond the content of the application as filed.
There is undue extension of the application when the modification does not arise directly and unambiguously from the information contained in the application as filed, taking into account the general knowledge of the person skilled in the art. French courts therefore use the “gold standard” defined by the EPO, with an approach similar to that of the Boards of Appeal. However, judges pay particular attention to the definition of a person skilled in the art, as discussed in reference to the inventive step.
The addition or removal of a feature may be considered an undue extension. An intermediate generalization – which consists of claiming, in the patent as granted, subject matter that is less than that which was filed, but that is more than the embodiments explicitly described in the disclosure or explicitly claimed – is also prohibited.277 An isolated feature therefore cannot be removed from a particular embodiment of the invention and added to the claim if it is inextricably linked to other features of this embodiment.278 Again, this is an approach similar to that taken by the Boards of Appeal.
13.4.2.4.2 The extension of protection
After being granted, and in accordance with Article L. 613-25(d) of the IPC and Article 123(3) of the EPC, a patent shall be declared null and void by judicial decision [...] when, after limitation, the protection conferred by the patent has been extended.
In order to demonstrate the extension of its scope, it is sufficient to show that the new claims cover a new element that initially fell outside the scope of the patent.
The means of assessment, which are indicated in the above provisions, are therefore similar to those applied before the EPO. The courts consider the scope of protection, taking into account the interpretation of claims by the person skilled in the art.
13.4.2.5 Annulment owing to absence of entitlement
Under Article 138(1)(e) of the EPC, a European patent may be annulled, in line with the law of a Contracting State, with effect in the territory of that state [...] if the owner of the European patent is not entitled under Article 60(1). The latter article provides that the right to a European patent shall belong to the inventor or their successor in title and that, if the inventor is an employee, the right to a European patent shall be determined in accordance with the law of the state in which the employee is mainly employed.
For domestic patents, French law does not provide that an action for annulment may be brought in the event of an invention being taken away from its inventor, but Article L. 611-8 of the IPC enables an inventor who has been unduly deprived of their industrial property title right, as well as their successors in title, to bring an action to claim the patent (see Section 13.4.4).
The absence of a right to an invention may only be brought before national courts after the patent has been granted. The provisions of Article 138(1)(e) of the EPC are interpreted by French courts to mean that, in order to protect the private interests of the lawful patent holder or their successor in title, their violation shall be punishable by relative nullity, which may only be invoked by the injured parties. As a result, a company that claims only that a patent relates to an invention made by an employee, the patent rights to which belong to the employer, is not entitled to bring an action for annulment of that patent.279
13.4.2.6 Absolute or partial annulment: legal limitations
The second paragraph of Article L. 613-25 of the IPC provides that if the grounds for annulment only partially affect the patent, annulment shall be pronounced in the form of a corresponding limitation of the claims. In the context of patent annulment proceedings, the patentee is entitled to limit the patent by amending the claims; the thus limited patent is the subject of the annulment action brought.280
Under Article L. 613-27(3) of the IPC, when a claim has been partially annulled in the decision the patent holder shall be referred to the INPI to present a draft of the amended claim in accordance with the provisions of the ruling. The INPI Director General has the power to reject the amended claim for failure to comply with the ruling, subject to an appeal to the Paris Court of Appeal.
13.4.2.7 Effects of annulment
Under Article L. 613-27 of the IPC, a ruling annulling an invention patent shall have absolute and retroactive effect, subject to opposition from third parties. Final decisions are notified to the INPI Director General so that they can be recorded in the National Patent Register.
In accordance with the above-mentioned provisions of Article L. 613-27 of the IPC, a ruling annulling one or several patent claims that has absolute effect must be recorded in the Register in order to be binding on all parties.
In practice, the ruling is recorded in the Register at the request of an interested party. The first instance ruling is recorded in the absence of an appeal, which requires a “certificate of non-appeal”; in contrast, the appeal decision may be recorded without waiting for a possible appeal in cassation.281
The defendant in an infringement action may also be limited to arguing the annulment of a patent as a means of defense by way of a plea, i.e., without filing a counterclaim. The annulment finding then only has effect between the parties and this plea in defense is not subject to any limitation, regardless of the provisions of Act No. 2019-486 of May 22, 2019.282 Annulment may also be argued through a plea in defense to an application for a provisional prohibition in summary proceedings,283 or to oppose a request for prohibition concerning national parties to a European patent other than the French party.284
Court of Cassation, Com., December 7, 2022, Appeal No. 20-21.102, issued in relation to trademarks, but transposable.
Court of Cassation, Com., February 14, 2012, Appeal No. 11-14.288, Bull. 2012, IV, No. 36.
Court of Cassation, Com., January 11, 2023, Appeal No. 19-19.567 and Paris Court of Appeal, March 26, 2025, RG No. 23/07392.
Paris Judicial Court, June 8, 2023, RG No. 21/12727.
European Patent Office, Enlarged Board of Appeal, October 10, 2023, G 1/22 and G 2/22.
Court of Cassation, Com., June 18, 1996, No. 94-18.909.
European Patent Office, Enlarged Board of Appeal, May 31, 2001, G 2/98.
European Patent Office, Enlarged Board of Appeal, November 29, 2016, G 1/15.
Court of Cassation, Com., March 12, 1996, Appeal No. 94-15.283; Court of Cassation, Com., June 6, 2001, Appeal No. 98-17.194; Court of Cassation, Com., March 26, 2002, Appeal No. 99-15.934; Court of Cassation, Com., May 14, 2013, Appeal No. 11-27.686; Court of Cassation, Com., May 17, 2023, Appeal No. 19-25.509.
Court of Cassation, Com., October 5, 2004, Appeal No. 03-10.580; Court of Cassation, Com., May 3, 2018, Appeal No. 16-25.578.
See, for example, Paris Court of Appeal, October 27, 2010, RG No. 09/08135; Paris Judicial Court, July 20, 2023, RG No. 21/10327; Paris Judicial Court, July 6, 2023, RG No. 21/10326.
Paris Court of First Instance, May 2, 2014, RG No. 11/17482.
The problem-solution approach consists in determining the prior art closest to the invention, then defining the objective technical problem to be solved, and finally examining whether the claimed invention, starting from the closest prior art and the objective technical problem, would have been obvious to the person skilled in the art.
Court of Cassation, Com., January 28, 2026, Appeal No. 23-16.425, paras 19 and 20.
Court of Cassation, Com., January 28, 2026, Appeal No. 23-16.425, paras 18 to 29.
Court of Cassation, Com., November 20, 2012, Appeal No. 11-18.440.
Court of Cassation, Com., November 20, 2012, Appeal No. 11-18.440.
Court of Cassation, Com., October 17, 1995, Appeal No. 94-10.433, Bull. 1995, IV, No. 232; Court of Cassation, Com., February 26, 2008, Appeal No. 06-19.149; Court of Cassation, Com., June 15, 2010, Appeal No. 09-11.931.
Court of Cassation, Com., October 17, 1995, Appeal No. 94-10.433, Bull. 1995, IV, No. 232; Court of Cassation, Com., March 19, 2025, Appeal No. 23-13.576.
Court of Cassation, Com., March 19, 2025, Appeal No. 23-13.576.
Court of Cassation, Com., June 23, 2015, Appeal No. 13-25.082, which accepts that a telescopic ladder specialist was encouraged to consult the documentation on telescopic masts.
See, for example, Paris Judicial Court, October 6, 2022, RG No. 22/55799.
Court of Cassation, Com., April 24, 2024, Appeal No. 22-15.379.
Court of Cassation, Com., March 17, 2015, Appeal No. 13-15.862; Court of Cassation, Com., March 19, 2025, Appeal No. 23-13.576.
Court of Cassation, Com., March 19, 2025, Appeal No. 23-13.576.
See, for example, Paris Court of First Instance, October 6, 2009, RG No. 07/16446; Paris Judicial Court, June 8, 2023, RG No. 21/12727 to align with the EPO Enlarged Board of Appeal decision of March 23, 2023, G 2/21.
For example, Paris Court of First Instance, October 6, 2009, RG No. 07/16446, mentioned above.
See, for example, Paris Court of Appeal, October 29, 2020, RG No. 20/07070.
See, for example, Paris Judicial Court, June 8, 2023, RG No. 21/12727.
For example, Paris Court of First Instance, October 6, 2009, RG No. 07/16446.
Court of Cassation, Com., May 18, 1999, Appeal No. 97-17.461.
Court of Cassation, Com., January 23, 2019, Appeals No. 17-14.673 and 16-28.322, which upheld that an engineer specializing in heating components for domestic heating appliances has basic knowledge of materials science and of insert molding techniques, and, in particular, has at least rudimentary knowledge of the iron-carbon phase diagram.
Court of Cassation, Com., December 6, 2017, Appeal No. 15-19.726, Bull. 2017, IV, No. 160.
Paris Court of Appeal, June 26, 2024, RG No. 23/16419.
Paris Court of Appeal, April 21, 2023, RG No. 15/14683.
Court of Cassation, Com., December 12, 2018, Appeal No. 17-16.419.
Court of Cassation, Com., February 14, 2012, Appeal No. 11-14.288, Bull. 2012, IV, No. 36.
For an example of application, see Court of Cassation, Com., November 15, 1994, Appeal No. 93-12.917; for a recent example of court validation of the limited claims proposed by the holder, see Paris Judicial Court, September 14, 2023, RG No. 22/08069.
Court of Cassation, Com., September 28, 2022, Appeal No. 20-16.874.
See, for example, Paris Judicial Court, October 6, 2022, RG No. 22/55799.
CJEU, February 25, 2025, Case C-339/22; see also Court of Cassation, First Civil Chamber, June 29, 2022, Appeal No. 21-11.085; CJEU, July 12, 2012, Case C-616/10.