Belgian labour laws set stringent language requirements which apply to the employers/employee relationship. In Flanders and Wallonia, all official employer-employee communications must be drafted in Dutch (Flanders) and French (Wallonia), otherwise the communication risks being null. The nullity sanction cannot however harm an employee who is still able to claim rights resulting from a null document, unlike the employer who will not.

In a judgment in January 2016, the Brussels Labor Court held that the nullity sanction was disproportionate when applied to an employment contract with a cross-border dimension, which was drafted in English only.

The case concerned an employee with dual Dutch/Spanish nationality, working for a company with a Belgian site (a branch), yet part of an international group of companies. The employee was dismissed for poor performance. The appraisal documents supporting the dismissal decision were drafted in English only. In an attempt to contest the grounds for dismissal, the employee claimed his contract and the appraisal documents supporting the dismissal decision were null and void, as pursuant to the applicable language requirements they should have been drafted in Dutch.

In its judgment, the Brussels Labor Court referred to earlier case-law of the European Court of Justice, stating that in cross-border employment situations the nullity sanction goes beyond what is strictly necessary to achieve the legal objectives set out by the language requirements (i.e. ensuring the employees fully understand the content of the contract). On this basis, the Labor Court ruled that, given the assumption that the employment contract had a cross-border dimension, the employee could not invoke the nullity of the appraisal documents.