Proving unfair competition: procedure and evidence 2026

Unfair competition is one of the most pernicious scourges of the business world, causing considerable harm to French companies every year. When a competitor adopts practices contrary to honest commercial usage, the victim must act quickly and methodically to assert its rights. However, proving unfair competition is a complex legal challenge that requires a rigorous evidential strategy and a procedure that is perfectly mastered.

The legal foundations of an unfair competition action

Unfair competition has its foundations in Article 1240 of the French Civil Code, which provides that "any act whatsoever of a person which causes damage to another obliges the person by whose fault it occurred to make reparation for it". This general provision applies to commercial relations where a professional adopts conduct contrary to fair trading practices.

An unfair competition action rests on three inseparable constituent elements. First, a fault characterised by conduct contrary to honest commercial usage. Second, loss suffered by the victim company, whether material or non-material. Third, a direct causal link between the fault committed and the damage found.

French case law recognises different forms of unfair competition, notably confusion, disparagement, disorganisation of the competing business and economic parasitism. Each type of unfair practice requires a specific evidential approach, adapted to the particular features of the conduct complained of. The most common forms of these practices and the remedies open to the victim are set out in question-and-answer form in our FAQ on unfair competition.

Identifying practices that amount to unfair competition

Confusion and slavish imitation

Confusion results from manoeuvres intended to create a misleading similarity between two businesses, their products or their services. This practice may take the form of imitating distinctive signs, packaging, colour codes or any other characteristic likely to mislead customers.

Slavish imitation, for its part, consists in faithfully reproducing the appearance of a competing product without making any significant innovation. Proving these practices generally requires a comparative technical expert report and the compilation of a detailed photographic file.

Disparagement and commercial defamation

Disparagement is characterised by the dissemination of inaccurate or biased information intended to harm a competitor's reputation. This practice may take various forms: malicious criticism, unfounded rumours, misleading comparisons or deliberately negative communication campaigns.

Proving disparagement requires careful preservation of all the material showing the dissemination of the statements complained of: publications, recordings, witness statements, screenshots or commercial correspondence.

Disorganisation of the competing business

This form of unfair competition aims to disrupt the normal functioning of a competing business by illegitimate means. It may take the form of mass poaching of staff, breach of confidentiality clauses, industrial espionage or interference with contractual relationships. Practical cases of disparagement, confusion and disorganisation, with the penalties imposed, are presented in our article on disparagement and disorganisation in unfair competition.

Building the evidence file

Admissible means of proof

In unfair competition matters, evidence is free and may be adduced by any means. This freedom of proof allows the use of written documents, witness statements, technical expert reports, reports by a commissaire de justice (bailiff) or digital material.

Evidence must nevertheless be obtained fairly and respect the rights of the defence. The use of unfair methods to obtain evidence may lead to the inadmissibility of the action or the nullity of the evidence.

The bailiff's report: an essential evidential tool

The bailiff's report is a preferred means of proof in unfair competition matters. It makes it possible to establish in an authentic and incontestable manner the reality of the practices complained of at a given time.

The bailiff may draw up reports on the internet, at points of sale, at trade fairs or in any other place where the unfair practices occur. The probative value of a bailiff's report is particularly high, unless material errors or procedural defects are shown.

Judicial and technical expert reports

An expert report often proves indispensable to analyse the similarity of products, assess the extent of loss or determine whether there is confusion. The judge may order an expert report of his or her own motion or at the request of the parties.

The appointed expert has extensive investigative powers and may carry out all necessary examinations. The report is evidence of the first importance, although the judge remains free to follow its conclusions or not.

Digital evidence and social media

The rise of digital technology has considerably changed the way evidence is built in unfair competition cases. Screenshots, web archives, search ranking data and traffic statistics are now unavoidable items of evidence.

Digital evidence must be built with care, respecting the requirements of authenticity and integrity. The use of digital certification tools or the involvement of a bailiff for digital reports strengthens the probative value of this material.

Court procedure and protective measures

Choosing the competent court

An unfair competition action falls within the jurisdiction of the judicial court (tribunal judiciaire), which rules in commercial matters where the action is between traders. The choice of the territorially competent court may prove strategic, several options generally being possible.

The victim may bring the matter before the court of the place where the harmful event occurred, that of the defendant's domicile or that where the damage was suffered. This plurality of jurisdictions makes it possible to optimise the procedural strategy.

Urgent summary proceedings

Where the situation is urgent and the manifestly unlawful disturbance persists, summary proceedings (référé) are an appropriate procedure. The judge in summary proceedings may order the immediate cessation of the unfair practices, subject to a penalty payment where appropriate.

Summary proceedings require showing urgency and the existence of a manifestly unlawful disturbance. They make it possible to obtain protective measures quickly pending the judgment on the merits.

Pre-action investigative measures (in futura)

Faced with the risk of evidence disappearing, it is possible to seek investigative measures in futura even before the main proceedings are commenced. These measures make it possible to have evidence recorded and preserved under the supervision of the judge. The preparation and execution of an application made without adversarial hearing are set out in our article on the ex parte application under Articles 145 and 493 of the French Code of Civil Procedure.

Assessing and compensating the loss

Quantifying material loss

Material loss resulting from unfair competition may take the form of lost turnover, reduced margin, additional costs or loss of customers. Quantifying it often requires an in-depth accounting expert report.

The chartered accountant will analyse the trend in the victim company's performance, taking account of external factors likely to influence results. Comparison with reference periods or similar businesses makes it possible to isolate the impact of the unfair practices.

Non-material loss and damage to image

Beyond material loss, unfair competition may cause non-material loss resulting from damage to the company's reputation. This loss, which is harder to assess, may nevertheless give rise to compensation.

The assessment of non-material loss relies on factors such as the company's profile, the extent to which the unfair practices were disseminated, their seriousness and their impact on the brand image.

Penalties and remedies

Civil penalties

The judge may order various remedies: compensatory damages, publication of the judgment at the defendant's expense, destruction of infringing products or an injunction to cease the unfair practices.

The penalty payment (astreinte) is an effective means of pressure to ensure that the measures ordered are carried out. Its amount must be proportionate to the stakes and sufficiently dissuasive.

Criminal penalties

Certain unfair competition practices may also constitute criminal offences: counterfeiting, defamation, breach of professional secrecy or misleading commercial practices.

The criminal route may prove complementary to the civil action, making it possible to obtain heavier penalties and to benefit from the investigative resources of the criminal justice system.

Frequently asked questions (FAQ)

What is the time limit for bringing an unfair competition action?

An unfair competition action is time-barred after five years from the day on which the victim became aware of the damage and the identity of its author. This limitation period may be interrupted by a formal notice or by the commencement of legal proceedings.

Can an unfair competition action be brought without being a direct competitor?

Yes, it is not necessary to be in direct competition in order to act. Case law recognises the action for businesses operating in related markets or likely to be affected by the unfair practices, provided that they suffer loss.

How to prove loss of customers due to unfair competition?

Proof of loss of customers may be established by comparing turnover before and after the unfair practices, by market studies, customer testimony or an accounting expert report showing the impact of the conduct complained of.

Are practices on the internet subject to the same rules?

Yes, unfair competition practices on the internet are governed by the same legal principles. However, building the evidence requires specific means: digital bailiff's reports, certified screenshots or metadata analysis.

What is the difference between unfair competition and counterfeiting?

Counterfeiting protects specific exclusive rights (trade mark, patent, design) whereas unfair competition penalises any conduct contrary to fair trading practices. The same practice may fall under both characterisations simultaneously.

Are summary proceedings always available in unfair competition cases?

Summary proceedings are available only in cases of urgency and manifestly unlawful disturbance. The judge checks that the conditions are met and that the measures sought are proportionate. The judge does not decide the merits of the dispute but orders protective measures.

How is the amount of damages assessed?

The assessment rests on quantifying the loss suffered: lost turnover, reduced margin, additional costs, non-material loss. An accounting expert report is often necessary to establish the causal link and to quantify the loss precisely.

The success of an unfair competition action rests on the quality of the evidential strategy and the rigour of the procedure followed. Given the complexity of these issues, support from a lawyer who practises in this field proves indispensable to optimise the chances of success and obtain compensation commensurate with the loss suffered. Do not hesitate to consult a professional to assess the merit of your action and define the strategy best suited to your situation.