Contractual fairness and the will’s role on the bindingness of contracts can be regarded as essential elements for the task of juridically argument that it is possible to find enough tools within the law of obligations to protect the contracting party that is in a weak position with respect to the other. In this sense, it is not necessary to have the status of a consumer to be entitled to the aforementioned protection, since such regime can be articulated from particular notions integrated to our legal system. In this framework, the modern interpretation of legitimate trust and contractual equilibrium are stressed. These notions can be inspired by the favor debilis criterion rather than the notion of good faith. This criterion is fundamental to define the directive line of this work.