A recording made without a party's knowledge is not automatically excluded from the proceedings in a civil case. Where a party so requests, the judge must weigh the right to evidence against the competing rights. But a partial recording, which is not disclosed in full and whose outcome remains unknown, is unusable: it is not indispensable to the right to evidence and is excluded from the proceedings.
The essentials
- Unfairly obtained evidence, such as a recording made without the other person's knowledge, is not automatically excluded in civil proceedings.
- The judge assesses the impact on the fairness of the proceedings as a whole, weighing the right to evidence against the conflicting rights at stake.
- Two cumulative conditions allow the production of evidence that interferes with other rights: it must be indispensable to the exercise of the right to evidence, and the interference must be strictly proportionate to the aim pursued.
- A recording of which only a fraction is disclosed, without the outcome of the conversation being known, is unusable and therefore not indispensable.
- The party producing a recording bears the risk of its incompleteness: the gap tells against that party.
A covert recording excluded by the lower court judges
The first civil chamber upholds the exclusion of a covert recording of which only part was produced (Civ. 1re, 4 March 2026, No. 25-17.582). A child was born abroad in 2023 to a man and a woman. In March 2024, the mother left for France with the child and refused to bring the child back to the country of birth. The public prosecutor (procureur de la République) applied to the family judge (juge aux affaires familiales) on the basis of the Hague Convention of 25 October 1980 on the Civil Aspects of International Child Abduction, seeking a declaration that the removal was wrongful and an order for immediate return.
Before the court of appeal (CA Colmar, 1 April 2025, No. 24/03487), the father, who had voluntarily intervened in the proceedings, produced a video recording made without the mother's knowledge and transcribed in the submissions. The mother applied for that document to be excluded as unfairly obtained. The lower court judges excluded it, noting that the conversation produced was partial and incomplete, that the recording was not disclosed in full and that the outcome of the exchange remained unknown.
The Cour de cassation (France's highest civil court) dismisses the appeal: a judge who finds that a recording is unusable thereby establishes that it was not indispensable to the exercise of the right to evidence. The decision first sets out the applicable rule (free translation).
It follows from Article 6, § 1, of the Convention for the Protection of Human Rights and Fundamental Freedoms and from Article 9 of the French Code of Civil Procedure that, in civil proceedings, unlawfulness or unfairness in the obtaining or production of evidence does not necessarily lead to its exclusion from the proceedings. The judge must, where an application is made to that effect, assess whether such evidence undermines the fairness of the proceedings as a whole, weighing the right to evidence against the conflicting rights at stake, the right to evidence being capable of justifying the production of material that interferes with other rights provided that such production is indispensable to its exercise and that the interference is strictly proportionate to the aim pursued.
The application to the case decided takes a single sentence.
Having thus made it clear that the recording produced, being unusable, was not indispensable to the exercise by [the father] of the right to evidence, the court of appeal was correct to conclude that it had to be excluded from the proceedings.
The second ground, directed against the refusal to order the child's return, is also rejected: the lower court judges were entitled to infer from their findings, in the light of the best interests of the child assessed in concrete terms, a risk of grave harm.
When does unfairly obtained evidence remain admissible?
Unfairly obtained evidence remains admissible where it is indispensable to the party producing it and the interference with the other party's rights remains strictly proportionate. The reasoning proceeds in two stages. The judge first considers whether production is indispensable, that is, whether the alleged fact cannot be established in any other way. The judge then checks that the interference with the competing rights, in particular the right to respect for private life, does not go beyond what the aim pursued justifies. The two conditions are cumulative.
The indispensable character is not presumed from the importance of the subject discussed in the recording. A document that does not establish what it purports to prove cannot be indispensable. That is precisely the case with a truncated recording: without knowing the beginning, the continuation or the outcome of the conversation, the judge can draw nothing reliable from it. Exclusion is then justified by the fact that the document is unusable, without any need to weigh the interference with private life any further.
What the decision confirms about the proportionality review
The decision confirms that the proportionality review is required of a judge hearing an application for exclusion, but that it may stop at the condition of indispensability. The appeal criticised the court of appeal for not having carried out the balancing exercise. The Cour de cassation answers that the findings on the partial nature of the recording show the absence of any indispensable character. The review was therefore carried out, albeit implicitly, and it stopped at the first condition, in the absence of which production cannot be allowed.
Two points remain open. The decision does not say at what degree of incompleteness a recording becomes unusable: the assessment remains that of the lower court judges, case by case. Nor does it indicate the fate of a complete and probative covert recording, which would then call for an effective balancing between the right to evidence and the right to respect for private life. As the case law stands at 4 March 2026, unfairness alone is enough neither to admit nor to exclude.
Points to watch for the party making the recording
A party intending to rely on a recording must anticipate two requirements: the completeness of the document and proof that no other means of evidence was available. A partial transcript reproduced in submissions does not replace disclosure of the recording in full. The opposing party will not fail to point out the cuts, and the court will conclude that the document proves nothing verifiable.
The application for exclusion, for its part, is better made expressly and with reasons. The balancing exercise is owed where it is requested of the judge. The party producing the document therefore has an interest in establishing, in its submissions, why it is indispensable: no written record, no witness, practical impossibility of obtaining the same information otherwise. These points apply to all civil litigation, including commercial litigation, where the decisive exchanges are often oral.
Checks before producing a recording in evidence
- Check that the recording is produced in full, from the beginning to the outcome of the conversation, and not through selected extracts.
- Identify the precise fact the document is intended to establish, and show that no other material in the file can establish it.
- Measure the interference with the other party's rights and limit it to what the aim pursued requires.
- Anticipate an application for exclusion by the opposing party and prepare, from the written submissions onwards, the justification for the indispensable character of the production.
- Prefer, wherever they exist, means of evidence that interfere with no rights: written confirmation, emails, witness statements.
Frequently Asked Questions
Can I record a conversation without telling the other person and use it in court?
A recording made without the other person's knowledge may be produced in civil proceedings, but its admission is never guaranteed. Where a party asks, the judge weighs the right to evidence against the competing rights. Production is allowed only if it is indispensable to the exercise of the right to evidence and if the interference remains strictly proportionate to the aim pursued. Both conditions must be met.
Is a partial recording worth anything before a French civil judge?
A recording of which only part is disclosed is very likely to be excluded. In the decision of 4 March 2026, the lower court judges noted that the conversation produced was partial, that the recording was not disclosed in full and that the outcome of the exchange remained unknown. The Cour de cassation concluded that this document, being unusable, was not indispensable to the right to evidence of the party producing it, and could be excluded.
Must the judge review proportionality even if no one asks?
The review is required of the judge where a party asks for it. The rule restated in the decision of 4 March 2026 expressly covers that situation: once a challenge is raised, the judge assesses whether the evidence undermines the fairness of the proceedings as a whole. A party seeking the exclusion of unfairly obtained material therefore has every interest in making an express and reasoned application in its submissions.
How can I prove the content of a verbal agreement with a business partner?
Written confirmation remains the safest route. A summary email sent after the meeting, minutes circulated to those who attended, or an exchange of messages restating the agreed terms are all easy to produce and hard to challenge. Statements from people present usefully complete the file. As a rule, evidence is prepared at the time of the negotiation, not at the time of the dispute.
What are the risks of producing unfairly obtained evidence in a commercial dispute?
The first risk is exclusion of the document, which leaves the case incomplete at the very moment proof is expected. The second is a credibility risk: a party relying on a questionable method weakens its entire argument before the court. As a rule, it is better to build the file on lawfully obtained material and to consider sensitive evidence only where no other means exists.