This article addresses the problem of the collision of fundamental rights in relation to the right to be tried within a reasonable time in tax proceedings, postulating, as a mechanism of solution, the possibility that the judge disregards the unconstitutional law and is loyal to the Constitution and international law in the application of the American Convention on Human Rights. Thus, the study will begin with the analysis of effective guardianship mechanisms, as a fundamental right in itself, and its relationship with the tax law material in tax procedures. Then, cases of normative collision will be studied in relation to the right to be judged within a reasonable period of time, to end with proposals for mechanisms of solution, considering the praxis in relevant judgments of Chilean courts. The methodology to be followed in this research is that of the legal sciences, which translates into the study of the tax legal norm and its ideological foundations, also considering the three dimensions of legal dogma proposed by Alexy.