Transversal Topics

Disciplinary Sanctions: Warning and Procedure in Luxembourg

The employer has powers of direction, supervision and sanction enabling them to impose disciplinary sanctions on employees. The warning is the most common sanction: it requires no legal formality, but produces an immediate extinctive effect — the employer may no longer invoke the same conduct to justify a subsequent sanction (non bis in idem principle). Special, more stringent regimes apply to staff delegates and to situations covered by a collective labour agreement.

Legal basis: Art. L.121-3; Art. L.162-12; Art. L.415-10 Updated: June 2026

1. The warning: nature and absence of formality

Basis in the employer's management powers

The employer may sanction an employee by means of warning letters under their management and direction powers. This power is inherent in the employment contract and does not need to be expressly provided for in the internal rules or the contract to be valid.

No legal formality required

The Luxembourg Labour Code does not specifically regulate warnings. No particular form is therefore required: a warning may be written or oral, although a written record is strongly recommended for evidentiary purposes. The absence of formal requirements does not diminish the legal effect of the sanction.

Although no formality is required, best practice is to issue the warning in writing, dated and signed, specifying the particular misconduct. This allows the employer to demonstrate, in the event of a later dispute, that a sanction was indeed imposed in respect of a specific act.

2. The non bis in idem rule: prohibition of double punishment

Extinctive effect of the warning

A fundamental principle governs the application of disciplinary sanctions: an employee may not be sanctioned twice for the same conduct. According to the ITM's position, if an employer has already sanctioned a specific act by way of a warning, the employer may no longer subsequently dismiss the employee by relying on that same act to justify the termination.

Exception: occurrence of a new act

The non bis in idem rule does not prohibit all dismissal following a warning. Dismissal remains possible where it is based on a distinct new act of misconduct occurring after the warning. The previous warning may then be used as contextual evidence to establish a pattern of behaviour, without itself constituting an independent ground for dismissal.

The Court of Appeal ruled a suspension (mise à pied) irregular because it was based on facts that predated a warning already issued, without any new grievances being relied upon (Court of Appeal, Ref. 146/23). The employer cannot "reopen" a matter already closed by a sanction.

3. Special regimes: staff delegates and collective agreements

Staff delegates: strictly regulated suspension procedure

The regime is considerably stricter for employees who benefit from protection by virtue of their representative mandate. In the event of serious misconduct, the employer may notify a suspension to the staff delegate, but must comply with the requirements of Article L.415-10 of the Labour Code:

›The decision must set out in precise terms the act or acts complained of and the circumstances justifying the serious nature of the ground;

›The acts may not be relied upon more than one month after the day on which the employer became aware of them, unless criminal proceedings were initiated within that same period.

This one-month period is a substantive condition: any grievance raised outside this period is inadmissible, regardless of the severity of the acts or the quality of the evidence.

Collective labour agreements (CLA)

Article L.162-12 of the Labour Code allows collective agreements to determine the conditions of dismissal and disciplinary sanctions, particularly in relation to harassment. However, the validity of such provisions is subject to the condition set out in Article L.121-3: any derogation from statutory provisions is only valid if it is more favourable to the employee.

Case law illustrates this limit: the Court of Appeal examined the legality of a salary demotion provided for by a CLA (Ref. 95/16), stressing that it could only be considered lawful if it proved more favourable to the employee than dismissal. A collectively agreed sanction cannot worsen the employee's position compared to the statutory framework.

4. Practical key warnings

Three essential rules for managing disciplinary powers safely:

›A warning exhausts the right to sanction in respect of the conduct concerned. Never issue a warning without measuring this extinctive effect, particularly if the conduct could potentially constitute serious misconduct.

›Staff delegates benefit from enhanced protection: the suspension procedure is subject to a one-month deadline and an obligation to specify the grievances precisely — any procedural defect may invalidate the sanction.

›CLA-based sanctions may not restrict employees' rights compared to the law. Any agreed demotion or suspension must always be assessed against the favourability principle (Art. L.121-3).

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The information in this guide is provided for informational purposes only and does not constitute legal advice. It may contain inaccuracies or may not reflect the latest legislative or case-law developments. For any specific situation, please consult a qualified legal professional.