Article 163 of Civil Code

1 - If a contract results in gross lesion to the State or another public legal person, to a person lacking capacity or having diminished capacity, or to an endowment, the injured party may request amendment of the other party's obligation, or of his own obligation, so as to remove the grossness of the lesion suffered. 2 - Lesion is considered gross if, at the conclusion of the contract, it exceeds one-fifth. 3 - A challenge on the ground of lesion is not precluded by the fact that the contract was concluded on behalf of the injured party by his lawful representative, or was authorized by the court.