This paper is a microcomparative study of the appeal for cassation on the merits based on Spanish and Chilean regulations. First, a genealogical analysis of the institution referred to is made in order to find a common root. Next, the main points regulated by Spanish and Chilean legislation in relation to the figure under study are mentioned. On the basis of the above, it is examined whether it is pertinent to transplant the appeal in cassation interest in our legal system. It is concluded that it is not advisable to incorporate this figure, since neither the uniformity of the jurisprudence nor the nomofilaxis ensures a fair result, since this depends on the fairness of the rule. On the other hand, it affects the right of the litigant, since it prioritizes the creation of doctrine over the resolution of conflicts, which is the main function of the jurisdiction.