Article 31, § 1 of the Act of 24 July 1987 on temporary work, temporary agency work and hiring out of workers for the benefit of users (the "Act on labour leasing") prohibits an employer from leasing his employees to a third party which uses these employees and has part of the authority over them that would normally pertain to the employer.

Hence, Belgian legislation departs from a prohibition of labour leasing. The essential condition for this prohibition to apply is that the employees are leased out and that, in this regard, there is a shift of part of the employer's authority from the initial employer (service provider) to the user.

These are the legal exceptions to the prohibition of labour leasing:

  • temporary work;
  • authorised labour leasing for a limited period;
  • labour leasing in the context of an employment project approved by the region;
  • labour leasing in the context of a group of employers;
  • specific exceptions in the public sector.

Article 33 of the Act on labour leasing also specifies that "any provision contrary to the provisions of this act and its implementing decrees is void in so far as it aims to restrict the employees' rights or to aggravate their obligations".

In a judgment dated 15 February 2016, the Supreme Court ruled that a violation of the Act on labour leasing resulted in the contract concluded between the service provider and the user being absolutely null, since the provision ordering the prohibition is a public policy provision. Hence, the service provider cannot claim the amount of the unpaid bills from the user.

Neither can the service provider's request be based on the unjust enrichment as mentioned in article 1131 of the Civil Code.

The Supreme Court indeed says that the judge can dismiss the impoverished party's claim, if he thinks that the preventive effect of the sanction, in case the parties concluded an agreement that is contrary to public order, would be put in jeopardy if he proceeded with this legal claim, or if he is of the opinion that the social order requires the impoverished party to be sanctioned more severely.

The judgment clearly shows the risk related to a violation of the Act on labour leasing. Nevertheless, it should be noted that in practice, companies are often poorly informed about the scope of the prohibition of labour leasing.

The Supreme Court ruled that the bills issued for a forbidden labour leasing were not payable.