The litigation surrounding the right to evidence has a new illustration in labour law. In a judgment delivered on 1st April 2026, the social chamber of the Court of Cassation ruled that documents obtained by an employee through an intrusion into the company's IT system were admissible in employment tribunal proceedings.
The facts of the case reflect a familiar situation. Temporarily suspended following a statement made against his employer, an employee argued that his dismissal constituted a retaliatory measure. To prove this, during his suspension, he accessed a manager's work computer and extracted three files, which he then produced before the labour tribunal. The Court of Appeal having rejected these documents on the grounds of their illicit nature, the social chamber overturned this analysis in its ruling no. 24-19.193 of 1st April 2026.
The Court's reasoning follows the line laid down by the plenary assembly on 22 December 2023, which had accepted that a civil judge could, under certain conditions, admit evidence obtained or produced unlawfully or unfairly. The social chamber recalls here that, to be admissible, such evidence must meet two cumulative requirements. Firstly, it must be indispensable for the exercise of the right of proof of the party invoking it, in the absence of any other means of evidence. Secondly, it must only infringe the opposing interest — here, the right to respect for private life of the director — to a strictly proportionate extent to the objective pursued. In this specific case, the Court notes that the employee had no other way to demonstrate the retaliatory nature of the dismissal and that he limited himself to producing three files. The interference with private life was, according to the legal judges, contained within admissible limits.
This decision has significant practical implications. It confirms that the line traditionally drawn between fair and unfair evidence is no longer, in itself, a bar to claims in an employment tribunal. However, as the ruling was made by a limited panel, without publication in the Bulletin, it is not being established as a leading case: its scope remains confined to the specific circumstances and requires careful interpretation. Employers would be well advised to anticipate these situations with a clear policy on managing IT access and traceability, while employees must ensure, before taking any investigative action, that they measure the truly indispensable nature of the means employed and restrict themselves to what is strictly necessary.
Ultimately, the social chamber is continuing the reorganisation of evidence law initiated at the end of 2023, confirming that procedural fairness is now, in strictly regulated cases, giving way to the effectiveness of the right to a defence.