Patent infringement writ of summons (assignation)

The patent infringement writ of summons is the document by which the patent holder brings proceedings before the Paris Judicial Court and sets out its claims against the alleged infringer. It is governed by Articles 54 and 56 of the Code of Civil Procedure and must, from the moment it is served, present the technical case in its final form, since the claim relied on and the scope of the alleged infringement define the framework of the proceedings.

The content of the infringement writ

The writ identifies the patent, the claims asserted and the products or processes concerned, then sets out the element-by-element comparison. It describes the harm suffered, formulates the requests for an injunction, recall, disclosure of information and an interim payment, and lists the exhibits. It mentions the steps taken towards an amicable resolution. Representation by a lawyer is mandatory, and the technical nature of the case usually calls for a patent attorney to work alongside the lawyer.

Immediate consequences

The date of the writ determines the starting point for interest and, often, the scope of the period for which compensation may be claimed. Where a saisie-contrefaçon has been carried out, the writ must be served within the time limit set by the regulatory part of the Code, failing which the seizure is void. The defendant responds with submissions that almost always include a counterclaim for invalidation of the patent, so that the validity of the title becomes the centre of the case.

Strategic choices

The claimant chooses between an action on the merits, anapplication for a provisional injunction and waiting for an opposition decision from the European Patent Office. It also decides how many defendants to sue (manufacturer, importer, distributor) and, for a European patent, whether to go before the Paris Judicial Court or the Unified Patent Court. A premature infringement writ based on a weak claim leads to the invalidation of the patent relied on.

Key points

An infringement writ is drafted after the validity analysis, not before. Any weakness in the asserted claim comes back as a counterclaim. The timetable, the choice of defendants and the choice of court are decided together, because they determine the length and cost of the dispute.

---

This glossary entry is general in scope and does not constitute legal advice.

Dhenne Avocats litigates patent disputes before the Paris Judicial Court, the Paris Court of Appeal and the Unified Patent Court. Where the question arises in a real case, the useful moment is almost always before proceedings are issued.

Patent litigation · Unified Patent Court · UPC case law · Tell us about your situation