The Cour de cassation rules unfair evidence admissible in civil proceedings

In two rulings dated December 22, 2023, the Cour de cassation abandoned the principle that evidence obtained unfairly is inadmissible in civil proceedings.

In both cases, an employee contested his dismissal for misconduct and the evidence presented by his employer to justify it: a transcript, made without the employee’s knowledge, of a meeting during which he was heard making disparaging remarks about his employer, or a private conversation with a colleague on the employee’s personal Facebook messaging system installed on his work computer used by another employee who reported this conversation to the employer.

While the appeal courts had ruled in favour of the employees, deeming the evidence in question inadmissible because it had been obtained by unfair means, the French Supreme Court has now censured this decision, reversing its long-established position.

The Cour de cassation points out that in criminal matters, there is no legal provision allowing the criminal court to disregard evidence produced by private individuals on the sole grounds that it has been obtained in an illicit or unfair manner, since the principle of fair evidence applies only to agents of the public authorities. The Cour de cassation notes that some legal scholars have pointed out the risk criminal proceedings be used to circumvent the more restrictive rules of evidence in civil cases.

The Cour de cassation now considers that, in civil proceedings, “the unlawfulness or unfairness in obtaining or producing evidence does not necessarily mean that it should be excluded from the proceedings. The judge must, when requested to do so, assess whether such evidence undermines the fairness of the proceedings as a whole, by weighing up the right to evidence against the conflicting rights involved, the right to evidence being able to justify the production of elements infringing other rights, provided that such production is essential to its exercise and that the infringement is strictly proportionate to the aim pursued“.

With this ruling, the Cour de cassation aligns its position with the European Court of Human Rights – recalled in detail in the three rulings – which, on the grounds of the right to evidence and equality of arms, does not, as a matter of principle, uphold the inadmissibility of unfair evidence, but requires the judge, in the event of a conflict between the right to evidence of one party and the rights of another, to weigh up the different rights and interests involved.

As a result, civil courts can now take into account evidence obtained unfairly. However, the admissibility of unfair evidence is subject to two cumulative conditions: (i) it must be the only possible way of proving the fact in question, and (ii) the infringement of the other party’s rights must not be disproportionate to the objective pursued.

In practice, while such a decision facilitates evidence, it also risks leading to a multiplication and lengthening of debates on the admissibility of such modes of proof, as trial judges will have to ensure the right balance between the conflicting interests at stake.

Cour de cassation, Assemblée plénière, December 22, 2023, no. 20-20.648 and 21-11.330

European Court of Human Rights, May 13, 2008, N.N. and T.A. v. Belgium, req. no. 65097/01







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