Intellectual property attorney in Paris

Dhenne Avocats is a firm dedicated to patent litigation. The point is worth making, because intellectual property covers trades that share neither the same courts, nor the same deadlines, nor the same instincts.

The firm argues patent disputes before the Paris Judicial Court, the Paris Court of Appeal and the Unified Patent Court. It handles the matters that attach directly to those cases: trade secrets and know-how, employee inventions, FRAND licences and standard essential patents, patent agreements.

It does not file titles, does not manage trade mark portfolios and does not run copyright or design litigation for its own sake. That work belongs to other practitioners, with whom the firm works regularly.

Three features set the patent apart from the other intellectual property rights and explain why it calls for a dedicated practice.

It is proved technically. Infringement is established claim by claim, by comparison with a product or a process, which means reading a technical text as the skilled person would read it at the priority date.

It can be attacked in defence. A defendant to an infringement action almost always raises the invalidity of the title, which opens a second trial inside the first. No other intellectual property right shows that symmetry so systematically.

It belongs to specialised courts. The Paris Judicial Court has exclusive jurisdiction in France (art. L. 615-17 of the Intellectual Property Code). Since June 2023 the Unified Patent Court has opened a parallel European route. Opposition before the European Patent Office is a third ground, with deadlines of its own.

A patent dispute regularly crosses others. The firm handles them where they attach to the case, not as a practice of their own.

• Trade secrets, in claim and in defence, including protection of the seized party's secrets during a saisie-contrefaçon.
• Unpatented know-how, often transferred by the same contracts as the patents.
• Copyright in software, where the same technical solution is claimed on two grounds.
• Unfair competition and free riding, where they are raised as related claims before the patent court.
• The additional remuneration owed to an employee inventor, and the classification of inventions.

The distinction is real and often misunderstood. The patent attorney drafts and files applications, runs examination proceedings and manages portfolios. The attorney-at-law appears before the courts, argues the case, conducts evidence measures and pursues the other side's liability.

In a contentious case both are involved, in distinct and complementary roles. The firm works routinely alongside the patent attorneys already in place, French and foreign, without displacing them.

The firm conducts the infringement action and the defence of the party sued, the revocation action, the provisional measures and obtains evidence through saisie-contrefaçon or the evidence measures of the Unified Patent Court.

It appears before the Paris Judicial Court, the Paris Court of Appeal and the Unified Patent Court, and coordinates with the patent attorneys who handle opposition and appeal proceedings before the European Patent Office. It also acts as local counsel in France and before the Unified Patent Court for foreign firms, and as arbitrator or counsel in disputes referred toarbitration.

Since 1 June 2023, a European patent taking effect in France may be defended before the Paris Judicial Court or before the Unified Patent Court, for as long as it has not been opted out. The choice is not neutral.

The Unified Patent Court sets itself the objective of ruling within a year and its decision covers every participating State, which multiplies the gain as much as the risk: the same judgment that stops the infringement everywhere may revoke the patent everywhere. The national route is slower, but it confines the exposure to French territory, which matters where the patent is fragile or where the activity at stake is concentrated there.

Which way to go depends on the strength of the patent, on where the infringer operates, on whether an opposition is pending before the European Patent Office and on the strategy of the opponent, who has the same menu. It is settled before proceedings are issued, almost never after.

Three items stand out. Fees, which follow the technical complexity of the case rather than the amount at stake. Technical costs, private expert opinions, translations, comparative testing, regularly decisive and regularly underestimated. Court costs lastly, which before the Unified Patent Court comprise a fixed part and a part based on the value of the dispute.

Part of those costs is recovered from the losing party, within the limits of what the court allows under article 700 of the French Code of Civil Procedure, and of the ceilings set before the Unified Patent Court. Estimating the cost, and what of it is recoverable, belongs to the first analysis just as much as reading the claims.

To that end the firm offers packages with a defined scope and budget, among them the second opinion and the litigation funding.

The useful moment is almost always before proceedings are issued. A cease-and-desist letter received, a competing launch announced, a saisie undergone, an opposition to prepare, a licence negotiation that hardens: each of these opens a short window, often a few weeks, in which the choices on evidence and forum are made.

A first conversation tells you whether an action is well founded, what it costs and what it exposes. It commits you to nothing.

Do you need an attorney at law or a patent attorney to sue for infringement?

Before the Paris Judicial Court and before the Unified Patent Court, representation belongs to the attorney at law. The patent attorney brings the technical analysis and the prosecution history, which makes cooperation between the two indispensable.

Does the firm file patents?

No. Filing, prosecution and portfolio management belong to patent attorneys. The firm works on the granted title, in attack, in defence and in the contracts that exploit it.

Can a patent be attacked without being sued first?

Yes. A revocation action requires no particular interest and is subject to no limitation period (art. L. 615-8-1 of the Intellectual Property Code). A company preparing a launch can therefore bring down a troublesome title before being sued.

How long does an infringement case take?

Before the Paris Judicial Court, count in years rather than months. Before the Unified Patent Court, the procedure aims at a first-instance decision in about a year. The actual timetable depends on the nullity raised in defence and on the evidence measures.

Can a European patent escape the Unified Patent Court?

Yes, through the opt-out under article 83 of the Agreement on a Unified Patent Court, filed during the transitional period and so long as no action has been brought before it. The opt-out may be withdrawn, but only once: withdrawal is barred if a national action has been brought in the meantime, and a proprietor who has withdrawn an opt-out may no longer file a new one.

Within what time must an infringement action be brought?

The action is time-barred five years from the day on which the proprietor knew or should have known the last fact entitling him to bring it (article L. 615-8 of the French Intellectual Property Code). Infringement that continues therefore remains actionable for the last five years. Time lost is paid for elsewhere, in the conviction of the court hearing an application for provisional measures and in the credibility of the loss alleged.

Does the firm act for foreign companies?

Yes, both as direct counsel and as local counsel in France and before the Unified Patent Court for foreign firms. Cases are handled in French and in English.

A cease and desist letter received, a competitor copying, a saisie announced, a patent to bring down before a launch: the earlier the firm is instructed, the more procedural options remain open. Tell us about your situation.

The firm has also structured offers and programmes with a defined scope: second opinion, litigation preparation, response protocol for a saisie-contrefaçon, trade secret audit, intellectual property due diligence, litigation funding.