Abstract
The adversarial criminal procedure regulated by law 906 from 2004 does not offer a differentiated juridical treatment, not before not during, to those who after having allegedly committed a crime are in a diminished or altered mental condition that prevents them to: i) understand the nature, object and consequences of the process, ii) collaborate effectively with their lawyer iii) exercise their right to material defense; legislative omission that is incompatible with due process of law. This article deals with this problem by conducting a critical analysis of the domestic procedural legislation and, therefore it proposes a solution to overcome the incompetency to stand trial and coherent with the foundations and limits of punitive power in a social democratic State under the rule of law.