Option Acceptance Formalities in Property Sale Promise

The dispute arose from a promise to sell a property which the promisor subsequently refused to finalize, arguing the offeree had not strictly complied with the required notification procedure for exercising the option to purchase. The Court of Cassation rejected the appeal, affirming that the formal requirement stipulated in the unilateral promise for the option holder to accept the offer via registered letter, effectively delivered, constitutes a condition precedent to the formation of the final contract, and failure to adhere to this precise mode of acceptance invalidates the exercise of the option.