In principle, the posting of workers from one employer to another is prohibited under Belgian Law. Only when certain strict conditions are complied with, is the posting of workers allowed. If these conditions are not fulfilled, the posting is null and void. Recently, the Supreme Court rendered a judgment and ruled that when the posting of workers between two employers is null (i.e. does not meet the strict conditions), the posting employer cannot demand payment of his invoices from the receiving employer. The argument that the receiving employer would be enriched without a cause, as he has made use of the posted workers, was not addressed by the Court.