Art. 22. Retroactive effect of penal laws. — Penal Laws shall have a retroactive effect insofar as they favor the persons guilty of a felony, who is not a habitual criminal, as this term is defined in Rule 5 of Article 62 of this Code, although at the time of the publication of such laws a final sentence has been pronounced and the convict is serving the same. (Revised Penal Code)
General Rule:  
Acts or omissions will only be subject to a penal law if they are committed AFTER a penal law has taken effect. Conversely, acts or omissions which have been committed before the effectivity of a penal law could not be penalized by such penal law. 


 Exception: 

 Penal laws shall have a retroactive effect, insofar as they favor the person guilty of a felony.


 Exception to the Exception:
(1) The new law is expressly made inapplicable to pending actions or existing cause of actions; or
(2) The offender is a habitual criminal.



 Habitual criminal 

Habitual criminal - is a person who within the period of 10 years from date of release or last conviction of the crimes of serious or less serious physical injuries, robbery, theft, estafa or falsification, he is found guilty of any said crimes a third time or oftener. (F-R-E-T-S-L)
Does Article 22 apply to special laws?

Yes. By force of Article 10 of the RPC, the beneficient provisions of Article 22 applies to and shall be given retrospective effect to crimes punished by special laws (People vs. Simon, G.R. No. 93028, July 29, 1994) 


May the favorable provisions of RA 7659 be given retroactive effect to entitle the offender to a lesser penalty?

Although Republic Act No. 6425 was enacted as a special law, albeit originally amendatory and in substitution of the previous Articles 190 to 194 of the Revised Penal Code, it has long been settled that by force of Article 10 of said Code the beneficient provisions of Article 22 thereof applies to and shall be given retrospective effect to crimes punished by special laws. The execution in said article would not apply to those convicted of drug offenses since habitual delinquency refers to convictions for the third time or more of the crimes of serious or less serious physical injuries, robo, hurto, estafa or falsification. (People vs. Simon)


Can the court sua sponte apply Article 22 even if not invoked by the accused?

Yes. The plain precept contained in article 22 of the Penal Code, declaring the retroactivity of penal laws in so far as they are favorable to persons accused of a felony, would be useless and nugatory if the courts of justice were not under obligation to fulfill such duty, irrespective of whether or not the accused has applied for it, just as would also all provisions relating to the prescription of the crime and the penalty. (People vs. Simon) 


Should penal laws be given retroactive effect as regard the jurisdiction of the court?

No. Because the jurisdiction of a court to try criminal cases is to be determined by the law in force at the time of the institution of the action and not at the time of the commission of the crime. (People vs. Pegarum, 58 Phil 715) 


Does retroactivity of penal laws apply to civil liability of the offender?

 No.