P.R. Laws tit. 33, § 4637
The criminal law has a retroactive effect in whatsoever favors the accused of a crime. Consequently, the following rules apply:
(a) If the law in effect at the time of the commission of the crime is different from that in effect when processing the accused or when imposing the sentence, the most lenient law shall always be applied.
(b) If during the term in which the person is serving the sentence a law that is more lenient with respect to the punishment, the security measure or the method of execution thereof takes effect, it shall apply retroactively.
(c) If during the term that the person is serving the sentence a law that suppresses the crime takes effect, or the Supreme Court issues a decision decriminalizing the act, the sentence shall be rendered null and the person freed from being incarcerated or under restriction of freedom.
In these cases, the effects of the new law or the new court ruling shall operate as a matter of law.
History —June 18, 2004, No. 149, § 9, eff. May 1, 2005.