Patent litigation: our core practice

Dhenne Avocats is a French firm dedicated to patent litigation. We represent manufacturers, laboratories, innovative SMEs and inventors before the Paris Judicial Court (the only French court with jurisdiction in patent matters) and before the Unified Patent Court (UPC). We act for claimants and defendants alike, in France and in coordination with our correspondents abroad.

Bringing an infringement action

Infringement proceedings (art. L. 615-1 et seq. of the Intellectual Property Code) allow the patent owner (and, on conditions, the licensee) to stop the unlawful working of the invention and obtain compensation. The case is built long before the writ is issued: analysis of the claims and of the products alleged to infringe (claim charts), gathering of evidence, forum strategy as between the French courts and the UPC, and coordination with any opposition proceedings before the EPO. The case is most often won in that preparatory phase.

We design the strategy, secure the evidence (in particular through a saisie-contrefaçon) and then run the proceedings through to enforcement of the decision, including on damages (Article L. 615-7 of the French Intellectual Property Code: negative economic consequences, the infringer's profits, moral prejudice).

You have been sued, or threatened with proceedings

A writ for infringement, a cease-and-desist letter or a French infringement seizure carried out against you calls for a swift and orderly response: analysis of the validity of the opposing patent and of the infringement allegations, a counterclaim for revocation, challenges to the seizure operations (application to set aside, discharge, protection of the trade secrets seized), and where appropriate the search for a negotiated outcome. The earlier the defence is engaged, the more options remain open.

Have you just been served or seized? Contact us without delay. The first few days shape everything that follows.

The revocation action

Revocation of the patent (art. L. 613-25 IPC, art. 138 EPC) is the mirror weapon of infringement: lack of novelty or inventive step, insufficiency of disclosure, added matter. It is brought as a main action (to clear a market) or in defence, by way of counterclaim. It calls for joint work between lawyer and engineer: prior art searching, technical reading of the claims, coordination with EPO proceedings (opposition, limitation). We practise this exercise in both directions, which feeds every attack we bring and every defence we run.

Provisional measures and urgency

Article L. 615-3 IPC allows an interim injunction against marketing, a seizure or the provision of security to be obtained in summary proceedings, provided that infringement is likely. Before the UPC, provisional measures (Article 62 UPCA) follow a logic of their own (proportionality, urgency, balancing of interests) which may work for or against the patentee. We argue these applications on both sides of the bar and systematically factor injunction risk into the overall case strategy, including its industrial dimension (stock, launches, customers).

Why a dedicated firm

Patent litigation is a matter of team and of repetition: reading the claims, working with patent attorneys and technical experts, and knowing the courts that actually decide these disputes, in Paris as in the divisions of the UPC. Our practice is matched by constant doctrinal work, made of academic publications and regular contributions on European patent litigation, which feeds into our written submissions. That is what our clients come for: a firm that does nothing else.

A patent dispute, as claimant or defendant? Let us talk now.

Further reading

Securing evidence: the French infringement seizure (saisie-contrefaçon)

The saisie-contrefaçon is the characteristic evidence-gathering measure of French patent law. It is ordered on an ex parte application, carried out by a commissaire de justice assisted where appropriate by an expert, and must be followed by proceedings on the merits within a short deadline, failing which the seizure is void. The scope of the order and the handling of sequestered material determine, in practice, the value of the evidence obtained, and how the seizure withstands an application to set it aside.

Which court

In France, patent disputes fall within the exclusive jurisdiction of the Paris Judicial Court. Since 1 June 2023, the Unified Patent Court hears actions relating to European patents with unitary effect and, subject to an opt-out, to classical European patents. The choice of forum, whether a national court, a local division or the central division, determines the territorial reach of the decision, the timetable and the exposure to revocation. It is settled before the action is brought, in light of the portfolio, the markets concerned and the risk of a counterclaim.

Standard-essential patents and FRAND commitments

A dispute over a standard-essential patent is fought first on contractual ground: the ETSI intellectual property rights policy is governed by French law, and the undertaking given by the proprietor has its source there. Before the question of the rate comes the question of the nature of the obligation, of who may rely on it, and of what it contains. The FRAND undertaking, a contract under French law.

Arbitration and mediation

The Agreement on a Unified Patent Court created, alongside the divisions, a mediation and arbitration centre. Not every question needs to be litigated: setting a rate, sampling a portfolio or handling confidential licences is often better resolved away from a public hearing. Arbitrer un litige de brevets en Europe.


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