Below is a comprehensive, plain-language overview of the legal provisions on adultery in the Philippines, drawn primarily from the Revised Penal Code (RPC) and related jurisprudence. This article will focus on the definition, elements, penalty, procedural concerns, and other significant matters necessary to understand this crime. While adultery remains a punishable offense under Philippine law, its prosecution has certain nuances that practitioners and laypersons alike should be aware of.

1. Definition and Legal Basis

Under Philippine law, adultery is governed by Article 333 of the Revised Penal Code (RPC). It specifically penalizes:

“Adultery is committed by any married woman who shall have sexual intercourse with a man not her husband, and by the man who has carnal knowledge of her, knowing her to be married.”

The essence of adultery, as defined by Philippine jurisprudence, is the voluntary sexual relationship between a married woman and a man not her husband. Notably:

The offense stresses the marital status of the woman. A married man’s similar behavior is addressed by a different offense—concubinage—under Article 334 of the RPC.
The third party (the paramour) must know that the woman is married. If he reasonably and honestly believes her to be single (through deception), a different legal question arises, although in practice it can be challenging to assert a successful defense based solely on ignorance if there were clear signs of marriage.

2. Elements of the Crime

For the prosecution to succeed, the following elements must be proven beyond reasonable doubt:

Existence of a valid marriage of the woman to another man at the time of the sexual act.
Sexual intercourse occurred between the married woman and another man (not her husband).
Knowledge on the part of the paramour that the woman is married.

Each act of intercourse constitutes a separate count of adultery. Thus, repeated acts can be charged as separate offenses, although proving each distinct act can be procedurally difficult.

3. Penalty Imposed

3.1. Principal Penalty

Under Article 333 of the RPC, the penalty for adultery is:

Prisión correccional in its medium and maximum periods.

In the technical terms of the Revised Penal Code:

Prisión correccional ranges from 6 months and 1 day to 6 years total.
The medium and maximum periods refer to roughly the middle to upper ranges within that span.

In practice, this translates to a penalty usually falling between 2 years, 4 months, and 1 day to 6 years in prison. Both the married woman and her paramour are liable to the same penalty.

3.2. Accessory Penalties

Aside from imprisonment, a person convicted of adultery may face accessory penalties imposed by the RPC, which could include:

Temporary special disqualifications (e.g., holding certain public offices)
Other accessory penalties depending on the length of the principal penalty

However, in the Philippines, the actual jail time imposed may be adjusted or suspended if certain post-conviction remedies or alternative sentencing (like probation, depending on the conditions) apply.

4. Private Nature of the Offense

Adultery is classified as a private crime in Philippine jurisprudence. This has several implications:

Only the offended spouse can initiate the criminal complaint. The State does not, on its own, bring charges for adultery.
Both offenders must be included in the complaint if they are both alive. The law requires that the husband (or offended spouse, if the roles were reversed under concubinage) sue both the spouse and the paramour together. Failure to include either one can result in the dismissal of the case or bar its institution.
Waiver or pardon by the offended party before or after the offense can extinguish criminal liability. A written pardon signed by the offended party is usually required and must be executed before the criminal action is filed or before final judgment.

5. Evidentiary Concerns

5.1. Proof of Intercourse

The prosecution must establish that sexual intercourse actually took place. Circumstantial evidence (such as hotel records, eyewitness accounts, or birth of a child within suspicious timing) is admissible, though direct evidence is more conclusive. In practice, many adultery cases hinge on circumstantial evidence that, taken together, proves the fact of intercourse beyond reasonable doubt.

5.2. Knowledge of Marriage

The paramour’s knowledge that the woman is married must likewise be proven. If there are overt circumstances that render ignorance implausible (e.g., open acknowledgment of a spouse, presence of wedding rings, or the woman’s statements), the defense that he did not know can be undermined.

6. Procedural Aspects

Complaint Affidavit: The offended spouse must file a complaint affidavit specifying the time, place, and manner of how the adultery was committed.
Prescription: Adultery prescribes in five (5) years. This means the criminal action must be filed within five years from the date the offended party discovered the offense.
No Double Jeopardy: Each act of adulterous intercourse can be charged separately. However, if the case for a specific adulterous act is dismissed or decided on the merits, another case for the same act cannot be re-litigated.

7. Relation to Other Family Laws

Legal Separation and Annulment: While adultery is often cited as a ground for legal separation in family courts, the existence (or non-existence) of an adultery criminal case does not automatically guarantee a favorable result in a legal separation or annulment suit. Different standards of proof and legal grounds apply in civil or family law proceedings.
Property Regimes and Succession: A spouse found guilty of adultery does not automatically lose inheritance or property rights, though the offended spouse may use it as basis in civil suits (e.g., damages claims, moral damages for emotional suffering).
Protection Orders: Under Republic Act No. 9262 (VAWC Law), adultery by itself is not the main subject of protection orders. However, in some complex domestic situations, the adultery case may intertwine with psychological or emotional abuse allegations.

8. Gender-Related Discussion: Adultery vs. Concubinage

8.1. Adultery (Wife’s offense)

Definition: A married woman having sexual intercourse with a man not her husband.
Penalty: Prisión correccional in its medium and maximum periods (2 years, 4 months, and 1 day to 6 years).
Elements: Must prove the fact of sexual intercourse and the paramour’s knowledge of her marital status.

8.2. Concubinage (Husband’s offense)

Definition: A married man commits concubinage when he keeps a mistress in the conjugal dwelling, cohabits with her in any other place, or has sexual intercourse under scandalous circumstances.
Penalty: Prisión correccional in its minimum and medium periods for the husband; destierro (exile) for the concubine.
Key Differences: The threshold for proving concubinage is different—merely proving sexual intercourse outside marriage is not enough for concubinage.

The disparity in the penalties and proof required has led to calls for reform and arguments that these provisions reflect outdated notions of gender inequality. However, as of this writing, both adultery and concubinage remain part of the Revised Penal Code.

9. Controversies and Calls for Reform

Gender Disparity: Some legal commentators argue that the law is harsher on women (adultery imposes a higher penalty vs. concubinage’s minimum and medium prision correccional).
Modernization of the Penal Code: Critics highlight the need to update the Revised Penal Code to address changes in societal values and to harmonize with constitutional provisions on gender equality.
Decriminalization Movement: Several sectors, including women’s rights groups, have proposed the decriminalization of adultery and concubinage, arguing that these are essentially marital or civil issues. As of now, no sweeping legislative reform has passed on this matter.

10. Key Takeaways

Adultery Remains a Crime: Despite the rarity of actual convictions and calls for reform, adultery is still on the books as a criminal offense in the Philippines.
Private Crime: Only the offended spouse can initiate the case, and both the spouse and paramour must be included as defendants for the case to proceed.
Penalty Range: Convicted individuals face a prison term generally between 2 years, 4 months, and 1 day up to 6 years.
Strict Proof Requirements: Proving adultery demands clear evidence of sexual intercourse and knowledge of the woman’s marital status.
Importance of Timing: A complaint must be filed within five years of the discovery of the offense; otherwise, it may no longer be prosecuted due to prescription.

Final Note

The crime of adultery in the Philippines is a vestige of historical legal frameworks that place a premium on marital fidelity, particularly for married women. While its continued inclusion in the Revised Penal Code shows the Philippines’ adherence to traditional norms, active enforcement is relatively uncommon, especially in urban areas where social mores are shifting.

Nevertheless, the law stands. Anyone involved in such a case, whether as a potential complainant or accused, should seek legal counsel promptly to understand the nuances, rights, possible defenses, and procedural requirements specific to their situation. Further legislative reforms could alter the landscape of this law in the future, but for now, Article 333 of the Revised Penal Code remains the chief reference point for the penalty for adultery in the Philippines.