By applying the vague and general provisions of the American Convention to concrete cases, the Inter-American Court of Human Rights has incorporated new rights ("implied rights") to the text of the treaty. In doing so, the Court has expanded its ratione materiae jurisdiction. The author argues that this practice challenges the main assumptions of the rule of law. In effect, the Court's creative activity has eroded the legality principle, by which adjudicators must follow the mechanisms and procedures of amendment previously defined by law. Finally, the article promotes judicial self-restraint by referring some factors whose ends are, precisely, to impose limits on the Court's powers.