1 General Part
Chapter 1- Criminal Law and its Application
Article 3
Operation in time of the criminal law
No one may be sentenced for an act that, according to the law into power at the time it was committed, did not constitute a criminal act.
A new law that does not incriminate a criminal act has retroactive effect. If the person has been sentenced, the enforcement of the sentence shall not commence and, if it has commenced, it shall cease.
If a law in force at the time when a criminal act has been committed differs from a subsequent law, the law whose provisions are more favorable to the person who has committed the criminal act shall apply
EDIT.