A new judicial doctrine in the field of penal law that abrogates a previous one must be applied prospectively and cannot be given retroactive effect if it would be prejudicial to an accused who acted in reliance on the old doctrine.

The case arose from a legal uncertainty created by two conflicting Supreme Court decisions regarding the illegal possession of firearms. The earlier doctrine, established in People vs. Macarandang, interpreted Section 879 of the Revised Administrative Code to include secret agents appointed by governors as "peace officers" exempt from firearm licensing requirements. A later case, People vs. Mapa, explicitly overturned this interpretation. The accused, Rafael Licera, was appointed as a secret agent and apprehended for possessing a firearm while the Macarandang doctrine was still in effect, but was tried and convicted after the Mapa doctrine had been established.

• On December 11, 1961, Rafael Licera was appointed as a secret agent by Governor Feliciano Leviste of Batangas.
• The appointment letter explicitly granted Licera the authority to possess a firearm in connection with his duties, citing the prevailing Supreme Court doctrine at the time.
• On December 2, 1965, the Chief of Police of Abra de Ilog, Occidental Mindoro, apprehended Licera for possessing a Winchester rifle, Model 55, Caliber .30, without the required license or permit.
• A complaint for illegal possession of a firearm was filed against Licera on December 3, 1965.
• A separate case for assault upon an agent of a person in authority, arising from the same apprehension, was also filed against him.
• The Court of First Instance conducted a joint trial for both cases, acquitting him of assault but convicting him of illegal possession of a firearm.

• Rafael Licera argued that his appointment as a secret agent in 1961 provided legal justification for his possession of the Winchester rifle.
• He contended that under the doctrine established in People vs. Macarandang, which was the prevailing law at the time of his appointment and apprehension, a secret agent was considered a "peace officer."
• As a "peace officer," he was exempt from the requirements of Section 879 of the Revised Administrative Code concerning firearm licenses.
• He asserted that the trial court erred in retroactively applying the newer doctrine from People vs. Mapa (1967), which was not yet established when the alleged crime was committed.

• The People of the Philippines, through the prosecution, implicitly argued that Licera's lack of a license for the firearm constituted the crime of illegal possession.
• The prosecution's position, which was adopted by the trial court, relied on the ruling in People vs. Mapa, which held that a secret agent is not a "peace officer" and is therefore not exempt from firearm licensing requirements.

• Procedural Issues:
  • N/A
• Substantive Issues:
  • Whether the judicial doctrine established in People vs. Mapa, which revoked the earlier People vs. Macarandang doctrine, should be applied retroactively to convict an accused who acted in reliance on the old doctrine.

• Procedural:
  • N/A
• Substantive:
  • The Supreme Court reversed the judgment of the Court of First Instance and acquitted Rafael Licera. The Court held that at the time of Licera's appointment as a secret agent in 1961 and his apprehension in 1965, the prevailing and controlling jurisprudence was the Macarandang doctrine. Under this doctrine, his appointment as a secret agent made him a "peace officer" exempt from firearm licensing laws, meaning he incurred no criminal liability. The Court reasoned that judicial decisions interpreting the law form part of the legal system and that the subsequent Mapa doctrine (1967) could only be applied prospectively. Applying the Mapa ruling retroactively would prejudice Licera, who had acted in good faith based on the law as it was then interpreted.

• Principle of Prospectivity of Judicial Rulings — The Court held that a new judicial doctrine that overrules a prior one should only apply prospectively and should not adversely affect individuals who had relied on the old doctrine in good faith. This principle is especially imperative in criminal law, where the punishability of an act must be reasonably foreseeable.
• Judicial Decisions as Part of the Law of the Land — Citing Article 8 of the Civil Code, the Court affirmed that its interpretations of the law are part of the legal system. Therefore, the interpretation in Macarandang was the effective law at the time Licera possessed the firearm, and he was entitled to rely on it.

• "Certainly, where a new doctrine abrogates an old rule, the new doctrine should operate prospectively only and should not adversely affect those favored by the old rule, especially those who relied thereon and acted on the faith thereof."

• People vs. Macarandang — Cited as the controlling precedent at the time of the alleged offense. This case established that a secret agent appointed by a provincial governor was a "peace officer" and thus exempt from firearm licensing requirements. The Court applied this doctrine to acquit Licera.
• People vs. Mapa — Cited as the case that revoked the Macarandang doctrine in 1967. The Court ruled that this later case could not be applied retroactively to Licera's situation.
• People vs. Jabinal — Referenced to support the ruling that a new judicial doctrine prejudicial to an accused cannot be given retroactive effect.

• Article 8 of the Civil Code — Invoked to establish that judicial decisions interpreting the law are part of the legal system of the Philippines, thereby giving the Macarandang doctrine the force of law at the time of the incident.
• Section 879 of the Revised Administrative Code — This was the central statute in the case, as it provides exemptions for "peace officers" from the legal requirements for possessing firearms. The entire dispute hinged on the interpretation of who qualifies as a "peace officer" under this section.