Context and procedural posture

Following a judgment of the Luxembourg Labour Tribunal delivered on 23 September 2025, the court clarified the computation of the statutory one‑month time limit for terminating an employment contract with immediate effect for gross misconduct (faute grave), particularly where the alleged misconduct is continuing in nature (faute « continuée »). The Tribunal also reiterated the limits on adducing internal documents in litigation.

One‑month time limit in cases of gross misconduct (faute grave)

Where gross misconduct consists of a continuing course of conduct persisting for more than one month and known to the terminating party from the outset, prior case law had diverged: one line held that the one‑month statutory period ran from the commencement of the culpable conduct; the other held that it ran only from the cessation of that conduct.

Relying on the Court of Cassation’s judgment of 9 February 2023, the Labour Tribunal held that the one‑month period in article L.124‑10(6) of the Labour Code runs from the moment the party acquires knowledge of the culpable facts, including where the misconduct is continuing. Accordingly, where the impugned conduct endures over time, the time limit does not await the end of the behaviour; it begins upon the first manifestation of the conduct known to the party invoking gross misconduct.

Applying these principles, the Tribunal rejected as unfounded and abusive an employee’s resignation with immediate effect for alleged gross misconduct by the employer, where the employee asserted that the employer had endangered him throughout the entire ten‑year employment relationship. The Tribunal found that, on the employee’s own case, he was aware from the outset of the alleged facts and should therefore have acted within one month of recruitment.

Production of documents in litigation: limits reaffirmed

The Tribunal confirmed that an employee may, in order to ensure his or her defence, produce internal documents of which he or she became aware in the performance of his or her duties. However, a confidential settlement agreement concluded with another employee at a time when the producing employee was no longer part of the workforce does not fall within that category and is therefore inadmissible as evidence.

Key takeaways

1. The one‑month period to invoke gross misconduct runs from the party’s knowledge of the relevant facts, even where the misconduct is continuing in nature. The period does not restart or defer until the conduct ceases.
2. Employees may rely on internal documents to defend their interests only where those documents were obtained through the performance of their duties. Confidential instruments obtained outside that context, such as a settlement concluded after the employee’s departure, are not admissible in evidence.