Yes.
By virtue of the principle of contractual freedom of the parties, they may, alongside compulsory details or clauses which must be included in any employment contract, insert additional clauses in their contract.
Examples
- non-competition clause;
- discretion clause;
- geographic-mobility clause;
- etc.
Article 1134 of the Civil Code lays down the principle that legally created agreements take the place of the law for those who created them.
That principle is valid also in employment law, unless the parties’ stipulations are intended to restrict the rights of the employee or render his obligations more severe, in which case the clause is deemed void and of no effect, pursuant to Article L.121-3 of the Labour Code.
In fact, Article L.121-3, mentioned above, provides that the parties to an employment contract are authorised to derogate from the provisions of the present title in a manner more favourable to the employee.
Article L.121-3 goes on to make it clear that any clause designed to restrict the rights of the employee or render his obligations more severe is void and of no effect.