Patent lawyer in Paris: file, license or assign an SME's invention.

In principle, no. Article L. 611-11 of the Intellectual Property Code defines the state of the art as everything made available to the public before the filing date, by written or oral description, use or any other means. A demonstration at a trade fair, an online video, a sales brochure or an offer sent to a customer without any confidentiality obligation can therefore be set against the application.

Article L. 611-13 disregards a disclosure made in the six months before filing in only two narrow cases: an evident abuse against the inventor, or a presentation at an official or officially recognised exhibition within the meaning of the 1928 convention, declared at the time of filing. An ordinary trade fair does not, on its own, fall within that scope.

However, a prior art disclosure destroys novelty only if it reproduces the invention in all its elements. The Court of Cassation reiterated this in approving a court of appeal that had distinguished a suction hose from an electric cable subject to different constraints (Cass. com., 15 October 2025, No. 24-10.010). The firm lists the communications already made and checks their exact content before fixing the filing date.

By a confidentiality agreement signed before the first technical meeting. It should identify the protected information, the purpose for which it may be used, the people authorised to know it and the duration of the undertaking. A dated annex listing the documents handed over makes proof easier in the event of a dispute.

Publication of the patent application does not release the partner from all its obligations. The Court of Cassation holds that “publication of a patent application discloses to the public only the technical characteristics and the information relating to the invention that it contains” (Cass. com., 17 May 2023, No. 19-25.007, our translation). It set aside the judgment that treated the agreement as lapsed upon publication, even though other exchanges remained covered.

The agreement is not enough to establish authorship of the invention. In a dispute in which a collaborator claimed that a company had filed his process, the Paris Court of Appeal noted that “the invention is protected only by what is set out in the claims” and dismissed the action, for lack of proof that the patented invention had been taken from him (CA Paris, pôle 5 ch. 2, 17 February 2023, No. 21/08764, our translation). The composition handed over in confidence was based on sodium citrate, whereas the patent concerned citric acid, and the court held that the two compounds are not interchangeable. The SME should therefore keep dated evidence that corresponds precisely to what it files.

Not as such. Paragraph 2 of Article L. 611-10 of the Intellectual Property Code excludes in particular mathematical methods, methods in the field of economic activities, computer programs and presentations of information, where the application relates to those items considered as such.

A recent decision illustrates the limit, to the applicant's detriment. The Court of Cassation dismissed the appeal against the rejection of an application concerning the display of the stages of a flight on a timeline (Cass. com., 7 October 2026, No. 25-15.279). It accepts the patentability of such a claim only “unless it refers to a technical device or means that produces a technical effect making a technical contribution to the problem set out in the patent application” (same judgment, our translation). The effect relied on must not depend on the user's subjective preferences.

For an SME developing embedded software, a control process or a sensor, the issue is therefore to identify the technical effect produced and to make it appear in the claims. Where the application shows no technical contribution, the patent route is closed and other forms of protection, subject to their own conditions, must be examined. The firm can study these options with the patent attorney in charge of the filing.

Under Article L. 611-14 of the Intellectual Property Code, an invention involves an inventive step if, to a person skilled in the art, it does not follow in an obvious manner from the state of the art. The choice of that person skilled in the art is often decisive.

The Court of Cassation states that “the person skilled in the art is the one in the technical field in which the problem arises that the invention, the subject of the patent, sets out to solve” (Cass. com., 19 March 2025, No. 23-13.576, our translation). It set aside, in favour of the patentee, a judgment that had taken a general electronics engineer as the person skilled in the art, although the invention concerned the electrical power supply of aircraft cabins.

It also frames reasoning by combining prior documents: “elements of the prior art destroy inventive step only if, combined with one another in a way reasonably accessible to the person skilled in the art, they would obviously have enabled that person to bring to the problem solved by the invention the same solution as the invention” (Cass. com., 24 June 2026, No. 24-14.680, our translation). For an SME, these criteria matter from the moment of filing: the description must set out clearly the technical problem and the advantage obtained, because these are what will be argued in the event of an opposition or an invalidity action based on Article L. 613-25.

It depends on its category. Article L. 611-7 of the Intellectual Property Code allocates to the employer inventions made in the performance of a contract that includes an inventive assignment corresponding to the employee's actual duties, or of studies expressly entrusted to the employee. The employee then receives additional remuneration set by the collective agreement, the company agreement or the contract. Other inventions belong to the employee, but the employer may have allocated to it those connected with the employee's duties or with the company's activities or resources, for a fair price.

The Court of Cassation accepts that the employer may assign its right in an invention made in the course of the employee's assignment: “the right to the patent on that invention belongs solely to the employer. No provision prevents the employer from assigning that right to a third party” (Cass. com., 5 January 2022, No. 19-22.030, our translation). In that case, the employee-inventor's claim for ownership against the assignee was dismissed.

A dispute over additional remuneration is not for the employment tribunal (conseil de prud'hommes). The Social Chamber approved the finding that the employment tribunal lacked jurisdiction, the action falling within the exclusive jurisdiction of the judicial court (tribunal judiciaire) (Cass. soc., 23 October 2024, No. 22-19.700). The SME should therefore put the invention declaration, the classification and the remuneration in writing as soon as technical staff are hired.

A writing, on pain of nullity. Article L. 613-8 of the Intellectual Property Code covers any transfer of the rights attached to an application or a patent, in whole or in part, as well as licences. A verbal agreement or an ambiguous exchange of emails leaves the transfer open to challenge: the writing must establish unequivocally the parties' agreement and the rights transferred.

In an infringement dispute, the Paris Court of Appeal examined a deed of assignment challenged by the defendant, who complained of the absence of the parties' addresses and registration numbers. It held that “the deed of assignment is indeed evidenced in writing as required by the last paragraph of Article L. 613-8 of the Intellectual Property Code” and declared the assignee entitled to bring proceedings for acts predating the assignment (CA Paris, pôle 5 ch. 1, 1 October 2025, No. 24/12410, our translation). The outcome also depended on the foreign law governing the contract, which rules out drawing a general rule from it.

For an SME, a useful deed of assignment specifies at a minimum the full identification of the parties, the application or patent numbers, the countries covered, the price and how it is paid, the assignor's warranties, the fate of earlier infringing acts and the obligation to record. The same care is needed for the contribution of a patent to a company's capital.

Because a deed that has not been recorded is not enforceable against third parties. Article L. 613-9 of the Intellectual Property Code requires the recording of all deeds transferring or modifying the rights attached to a patent, except as against a third party who knew of the deed when it acquired its own rights.

The consequence is concrete for the buyer. The Court of Cassation holds that “until the transfer has been recorded in the register, the successor in title cannot rely on the rights arising from the deed that transferred ownership of the patent to it” (Cass. com., 24 April 2024, No. 22-22.999, our translation). The buyer therefore cannot bring an infringement action before recording.

Once the recording is made, the regularisation takes effect. The same decision allows compensation for acts committed since the transfer and, “if the deed transferring the rights so specifies, for the harm caused to it by acts committed before the transfer” (Cass. com., 24 April 2024, our translation). The clause in the deed on earlier acts therefore has direct effect.

The same article nonetheless allows a licensee whose contract is not recorded to intervene in the infringement proceedings brought by the holder, in order to obtain compensation for its own harm. The firm checks the register extract before any purchase and arranges the recording as soon as the deed is signed.

Article L. 613-8 of the Intellectual Property Code allows an exclusive or non-exclusive licence to be granted, in whole or in part. The holder may enforce the patent against a licensee who exceeds the limits of the licence, for example by exploiting outside the territory, field of application or duration provided for.

The choice changes how the patent is defended. Under Article L. 615-2, the exclusive licensee may bring an infringement action, unless the contract provides otherwise, provided it informs the holder beforehand; the non-exclusive licensee may do so only if the contract expressly authorises it, and it too must inform the holder beforehand, on pain of inadmissibility. The validity of the patent cannot be challenged in the licensee's action if the holder is not a party to the proceedings.

Exclusivity calls for something in return: an obligation to exploit, minimum royalties, sales targets, a right to take back exclusivity in the event of non-performance. Where the patent belongs to several co-owners, an exclusive licence requires the agreement of all of them or court authorisation (Article L. 613-29). The firm drafts the territory clause, the fate of improvements and the allocation of infringement actions according to the SME's business model, whether it is licensor or licensee.

The contract must set the basis, the rate, the frequency, the proof of sales and the penalties for late payment. Recent case law shows that these clauses are applied as written, which means they must be drafted precisely.

In an exclusive licence providing for a percentage of sales and a monthly minimum, the Paris Court of Appeal held that the minimum remained due even without sales, the parties having agreed a guaranteed minimum “applying, even in the event of non-exploitation, for the contractual term of three years” (CA Paris, pôle 5 ch. 1, 5 March 2025, No. 22/10410, our translation). It refused to treat this as a penalty clause, the stipulation being intended “not to penalise the breach of an undertaking but to compensate on a lump-sum basis a shortfall in royalties” (same judgment, our translation). The licensee was ordered to pay.

For its part, the Riom Court of Appeal noted that the licensee had undertaken to keep separate accounts for the exploitation and held that it could not make payment of the royalties conditional on the patentee issuing invoices (CA Riom, ch. com., 5 November 2025, No. 24/01527). These decisions rule on particular contracts: the rates and amounts they mention are not a benchmark. The firm provides for an audit right, periodic statements and a suitable termination clause.

Annual fees must be paid when due, with a six-month grace period on payment of a surcharge (Article L. 612-19 of the Intellectual Property Code). After that period, the holder forfeits its rights as of the unpaid due date (Article L. 613-22).

An application for restoration exists, but it is bound by strict time limits. Article L. 612-16 requires a legitimate excuse and an application made within two months of the end of the impediment, the period within which the omitted act must also be performed. The application is admissible only within the year following the expiry of the time limit not observed, which, for an annual fee, means the six-month grace period; restoration also requires payment of the fees due within the regulatory time limit.

The Court of Cassation applies these time limits strictly, to the patentee's detriment. It holds that “the notification of the decision recording the forfeiture of a patent, whether made to the patentee or to its representative, puts an end to the legitimate excuse” (Cass. com., 17 May 2023, No. 22-10.744, our translation). An application made more than two months after that notification was declared inadmissible, and the representative's default was not accepted as an excuse for the holder.

An SME should therefore keep a calendar of annual fees for each country, appoint an internal person responsible and check the notices sent by its representative. In an assignment or a licence, the contract states who pays the annual fees.

A joint filing with a laboratory, a customer or a partner creates a co-ownership governed by Article L. 613-29 of the Intellectual Property Code. Each co-owner may exploit the invention for its own benefit, subject to fairly compensating those who do not personally exploit the invention or have not granted a licence. Each may bring an infringement action for its own benefit, provided the writ of summons is notified to the others.

Licences are subject to a more demanding regime. A non-exclusive licence requires the plan to be notified to the other co-owners together with an offer to sell the share at a stated price; they have three months to object by buying that share. An exclusive licence requires the agreement of all or court authorisation. The assignment of a share gives rise to a three-month right of pre-emption.

These rules apply only in the absence of contrary provisions, and the co-owners may depart from them at any time by means of co-ownership regulations (Article L. 613-32). For an SME, these regulations are often the most useful deed of a research partnership: they set out who files, who pays the annual fees, who exploits in which field, how royalties are shared and what happens if a partner leaves.

Article L. 611-8 of the Intellectual Property Code provides an action for ownership where the patent was applied for in respect of an invention taken from the inventor or in breach of a legal or contractual obligation. It is subject to a five-year limitation period running from publication of the grant, or from expiry of the patent where there was bad faith when the patent was granted or acquired.

Until that action succeeds, the applicant retains certain prerogatives. The Court of Cassation holds that the applicant, even if it knew it was not entitled to the patent, has “until any action for ownership brought against it succeeds, standing and an interest to bring an infringement action against any third party” (Cass. com., 24 June 2026, No. 24-14.680, our translation). The ownership action should therefore be brought without delay.

The burden of proof remains on the claimant. In the case decided by the Paris Court of Appeal on 17 February 2023, the action was dismissed because the documents produced did not correspond to the invention as claimed (CA Paris, pôle 5 ch. 2, 17 February 2023, No. 21/08764). The firm gathers the dated documents, signed agreements and exchanges that establish the origin of the invention, then compares them with the published claims before acting.

Without the holder's consent, the manufacture, offer, placing on the market, use, import, export or possession for those purposes of the patented product are prohibited (Article L. 613-3 of the Intellectual Property Code). Any breach of those rights constitutes infringement giving rise to the civil liability of its author (Article L. 615-1). The same provision, however, holds a person other than the manufacturer liable, for offering, placing on the market, using or possessing the product, only if that person acted knowingly.

Evidence is prepared before the writ of summons is served. Article L. 615-5 allows a detailed description or a seizure of the products or processes alleged to infringe to be carried out on an order issued on application. To set damages, the court takes into account separately the negative economic consequences, including lost profits and losses suffered, the non-material damage and the infringer's profits, including its savings on investment. At the injured party's request, it may instead award a lump sum higher than the royalties that would have been due, without excluding compensation for non-material damage (Article L. 615-7).

The action is subject to a five-year limitation period running from the day the holder knew or should have known the last fact enabling it to bring the action (Article L. 615-8). It falls within the jurisdiction of the Paris judicial court (tribunal judiciaire), in the cases and on the conditions laid down by the Code (Article L. 615-17 and Article D. 211-6 of the Code of Judicial Organisation). Before acting, the SME checks that the patent is recorded in its name, that the annual fees are paid and that the rights of action granted to licensees by contract are identified: these are the first points the defence will raise.