De vrijwillige wijziging van de inhoud van het contract De vrijwillige wijziging van het contract

Sometimes contracting parties or a third party want to modify the content of a contract while still maintain the existence of the contract.

This raises the question as to what types of changes can be made while maintaining the existence of the contract. We came to the conclusion that some changes are by nature incompatible with the maintenance of the existence of the contract, i.e. the addition or removal of essential elements of the contract resulting in its requalification and the replacement of essential contractual elements.

Our second research question addressed when and under what conditions one of the contracting parties or a third party can unilaterally modify the contract?

The unilateral variation is, in principle, prohibited. However,  a number of exceptions to this rule exist. First, we think of the unilateral modification clauses. Such clauses are valid provided they do not exceed the limitations imposed by the legislator. In the absence of a unilateral modification clause, a unilateral variation is only possible in a limited number of cases. A first example is the possibility for the principal or the client to unilaterally remove elements respectively from the agency or service contracts. Another example is the possibility for the franchisor to unilaterally change the commercial concept on which the franchise is based. Finally, faced with difficulties that require an urgent modification of the contract, the agent and the service provider can unilaterally change the service to be provided if they cannot consult respectively the principal and the client in advance.

In the absence of a faculty of unilateral variation, good faith provides relief to the party seeking a contract modification. Indeed, the moderating and complementary effects of good faith can, in some cases, compel one of the contracting parties to accept a proposed modification and prohibit it from seeking the unmodified performance of the contract.

Like the unilateral variation, the modification of the contract by a third party is possible only if it is authorized by a statute or by a contractual clause. Where such a clause does not designate the third party and does not specify the procedure for such designation, the faculty to modify the contract must be governed by objective criteria. In the absence of such criteria, the object of the obligations to which the clause relates must be regarded as indeterminate.

Our third research question (What are the consequences of the modifying legal act?) led us to distinguish between the consequences of the regular and irregular modifying legal act.

If the modifying legal act is regular, the contract is modified. The modification is not limited to the content of the contract. It may also lead to a change in the applicable law when a new statute has entered into force between the time of the conclusion of the contract and the time of its modification. Furthermore, the modification of the contract also affects the security rights related to the modified contract. In principle, the person who has vested a security right can always rely on a favorable modification. This person is moreover rarely adversely affected by the addition of a new obligation or the aggravation of existing obligations.

In principle, the irregular modifying legal act does not modify the contract. The irregularity of the modifying legal act implies that the party who performs a contract according to the new conditions is not correctly performing the contract. Moreover, the judges can sometimes infer an implicit termination from an irregular unilateral legal act.