Title II
Rights
CHAPTER EIGHT
Rights to protection
Article 76. In all processes where rights and obligations of any kind are set forth, the right to due process of law shall be ensured, including the following basic guarantees :
3. No one shall be judged or punished for a deed or omission which, at the time of its perpetration, is not legally classified by law as a criminal, administrative or other offense ; nor shall a punishment not provided for by the Constitution or law be applied. A person can only be judged by a competent judge or authority and in keeping with the procedures corresponding to each proceeding.
Non-retroactivity
Nullum crimen sine lege
Nulla poena sine lege
EDIT.