This study will analyse the optional vote for voters aged over 16 and under 18, with the aim of thoroughly analysing art. 14, § 1, II, c, of the Federal Constitution. However, this analysis is not restricted to the aforementioned legislation, but also to highlight the precepts of infra-constitutional legislation, namely our Penal Code, more specifically art. 27, since it is through this that criminal unimputability is described, and also art. 107 of the Statute of the Child and Adolescent (ECA).