The problem of constitutional control of pre-constitutional legislation has been relevant in Chile from the moment a centralised model of constitutional control was established. The Supreme Court has declared the unconstitutionality of the said legislation by implied repeal, while the Constitutional Court has argued the opposite. Thus, nowadays, the debate is far from be resolved. Hence, firstly, this paper analyses the conceptual differences between repeal and unconstitutionality. Secondly, it tries to systematize the debate concluding that there is an equilibrium between both positions, with the exception of the use of comparative law. This argument has been frequently used by the Supreme Court; however, it has been not discussed in depth. For this reason, the last part of this work criticizes the way in which the Supreme Court uses comparative law on the basis of its limited methodological rigour. Finally, it is concluded that it is necessary to redirect this debate towards another kind of analysis.