Below is a comprehensive discussion of the offenses of adultery and concubinage under Philippine law, with a focus on how these crimes are defined, who may be arrested, and under what conditions arrests may legally occur. This article is for general informational purposes only and should not be taken as legal advice. For specific concerns, it is always best to consult with a qualified lawyer.

1. Legal Basis

1.1. Adultery (Article 333 of the Revised Penal Code)

Under the Revised Penal Code of the Philippines (RPC), adultery is committed by a married woman who has sexual intercourse with a man who is not her husband. The man who has carnal knowledge of her—knowing she is married—also commits the same offense.

The elements of adultery are:

The woman is legally married.
She engages in sexual intercourse with a man who is not her husband.
The man knows that she is married.

1.2. Concubinage (Article 334 of the Revised Penal Code)

Meanwhile, concubinage is committed by a married man when:

He keeps a mistress in the conjugal dwelling; or
He has sexual intercourse under scandalous circumstances with a woman not his wife; or
He cohabits with her in any other place.

A key distinction from adultery is that the standard of proof regarding a husband’s “other relationship” can be more difficult to establish, as the law requires “scandalous” circumstances or a degree of permanence or publicity (e.g., living together, or bringing the mistress into the family home).

2. Nature of the Crimes: Private Offenses

Adultery and concubinage are considered private crimes in Philippine law. This means:

Only the offended spouse (the legal husband or legal wife) can file a criminal complaint.
The complaint cannot be initiated by the government, a concerned relative, or any private third party (except in the limited scenario where the offended spouse has died or becomes incapacitated, in which case certain heirs may sometimes pursue the case, subject to legal requirements).
Both parties to the offense (the offending spouse and the paramour or mistress) must generally be included in the complaint for adultery or concubinage. The offended spouse cannot file a charge against only one party and exclude the other, unless one of them is outside the jurisdiction of the court or for other lawful causes.

3. Arrest Requirements and Procedures

3.1. Ordinary Procedure: Preliminary Investigation and Warrant of Arrest

Because adultery and concubinage are criminal offenses under the RPC, the ordinary procedure to arrest those accused is:

Filing of a Complaint-Affidavit: The offended spouse files a sworn complaint-affidavit (along with supporting evidence) before the Office of the City or Provincial Prosecutor.
Preliminary Investigation: The Prosecutor’s Office conducts a preliminary investigation to determine whether there is probable cause to charge the accused in court. This involves:
- Requiring counter-affidavits from the respondents (the offending spouse and the alleged paramour/concubine).
- Possible clarificatory hearings if needed.
Filing of Information in Court: If the prosecutor finds probable cause, an Information (formal charge) is filed in the appropriate trial court.
Issuance of a Warrant of Arrest: The court, upon reviewing the case, may issue a warrant of arrest if it finds probable cause. The parties named in the warrant can then be arrested by law enforcement authorities.

Note on Private Crimes:

Because adultery or concubinage is a private offense, the complaint cannot proceed without the offended spouse’s formal participation. Further, if the offended spouse decides to pardon or condone the offense (before the court has rendered a final judgment), the case may be dismissed—provided that both parties are pardoned, not just one.

3.2. Warrantless Arrest: In Flagrante Delicto

Under Philippine law (Rule 113, Section 5 of the Rules of Court), warrantless arrests may only be made under exceptional circumstances, such as:

In flagrante delicto (the person to be arrested has just committed, is actually committing, or is attempting to commit an offense in the presence of the arresting officer).
Hot pursuit (the offense has just been committed, and the officer has personal knowledge of facts indicating the arrestee committed it).
Escapee (the person to be arrested has escaped from a penal establishment or from detention).

For adultery or concubinage, an in flagrante delicto scenario would typically involve catching a married person and the third party in the act of sexual intercourse under circumstances so immediate and evident that law enforcement personally witnesses it. This is extremely rare in practice. Even then, the offended spouse’s participation is critical for prosecution, and other legal issues (e.g., privacy rights, trespassing) may arise if attempts to gather “evidence” violate the law.

Given that adultery and concubinage are inherently intimate and private crimes, it is unusual and complicated to effect a valid warrantless arrest. Most cases follow the ordinary procedure (complaint, preliminary investigation, and warrant issuance).

4. Evidentiary Requirements

4.1. Adultery

Direct proof of sexual intercourse: This can be challenging, but circumstantial evidence (e.g., hotel receipts, eyewitness accounts, photographs, text messages, or other communications that strongly suggest a sexual relationship) can be presented.
Witness testimony: The offended spouse may present witness statements corroborating the extramarital relationship.

4.2. Concubinage

Scandalous Circumstances: The law requires that the husband’s conduct (if not in the conjugal dwelling) be “under scandalous circumstances”—meaning it must be so public and notorious that it offends the moral sense of the community.
Proof of Cohabitation: If the husband and the mistress are cohabiting, documentary and testimonial evidence (utility bills, rental contracts, neighbors’ testimonies) may be relevant.
Keeping a mistress in the conjugal dwelling: Proof may include testimonies of household members, neighbors, or other tangible evidence that the mistress resides in the family home.

5. Penalties

5.1. Adultery (Article 333)

Both the married woman and her paramour are subject to the same penalty under the law:

Prison correctional (generally from 6 months and 1 day to 6 years).
The exact duration is determined by the court after considering the circumstances of the case.

5.2. Concubinage (Article 334)

The husband faces the penalty of prisión correccional (6 months and 1 day to 6 years). However, the mistress may face the lesser penalty of destierro (exile), which prohibits her from residing or entering certain places specified by the court.

6. Defense Considerations and Special Issues

Pardon by Offended Spouse: A complaint for adultery or concubinage cannot prosper if the offended spouse has expressly or impliedly pardoned both offenders. The pardon must be granted to both parties; pardoning only one is invalid.
Prescription Period: There is a time limit (prescriptive period) for filing these cases. For adultery and concubinage, the prescriptive period is relatively short (generally 5 years). This means the offended spouse must file within 5 years from the date of commission or discovery, subject to legal nuances and judicial interpretation.
Proof of Valid Marriage: The prosecution must prove that the offended spouse and the accused spouse are legally married. If the marriage is null and void from the start (e.g., bigamous marriage declared void by a final judgment), the adultery or concubinage charge cannot stand.

7. Practical Tips and Reminders

Gather Solid Evidence: Since these offenses are private and heavily reliant on evidence of a very personal nature, the offended spouse should ensure documentation (photos, witness affidavits, text messages) is legally obtained and can be authenticated.
Proceed with Caution: Accusing a spouse of adultery or concubinage can have serious repercussions—not only criminal charges but also implications in civil and family law (e.g., custody, property relations).
Consult a Lawyer: The procedural and evidentiary complexities of adultery and concubinage cases make professional legal guidance crucial. A lawyer can clarify your rights, help gather evidence, and ensure compliance with procedural rules.

8. Conclusion

Adultery and concubinage in the Philippines are criminalized under Articles 333 and 334 of the Revised Penal Code, respectively. These are private crimes that can only be prosecuted upon the complaint of the offended spouse. The typical route for arrest involves a formal complaint, preliminary investigation, filing of information in court, and the issuance of a warrant of arrest—rather than a warrantless arrest. The standard of proof is high, and the process can be emotionally and legally challenging. As with any legal matter, individuals who suspect or experience marital infidelity and are contemplating criminal action should seek professional legal advice to navigate the complexities of these offenses.