I. Overview

In the Philippines, marital infidelity is not just a moral issue – it can be a crime. The Revised Penal Code (RPC) punishes:

Adultery – when a married woman has sexual intercourse with a man who is not her husband.
Concubinage – when a married man engages in certain forms of sexual relations/cohabitation with a woman who is not his wife.

These are private crimes, meaning the State cannot prosecute them on its own. Only the offended spouse can validly initiate the case, and there are strict technical rules about who can be charged, when, and how.

This article walks through:

The legal definitions of adultery and concubinage
Key differences between the two
Who can file, against whom, and under what conditions
How to actually file a case
Other civil and family-law remedies related to infidelity

This is general legal information, not a substitute for advice from a Philippine lawyer who can examine your specific situation.

II. Legal Bases (Philippine Context)

The main laws are:

Revised Penal Code (RPC)
- Article 333 – Adultery
- Article 334 – Concubinage
- Article 344 – Prosecution of private offenses (including adultery & concubinage)
Family Code of the Philippines
- Grounds for legal separation and nullity/annulment
- Rules on support, custody, and property relations

III. Adultery

A. Definition and Elements

Under Article 333, adultery is committed when:

A married woman
Has sexual intercourse
With a man not her husband
The intercourse occurs during the subsistence of a valid marriage
The man knows that the woman is married

Important notes:

The offender-wife and her paramour are both criminally liable.
Every sexual act is a separate crime of adultery. Ten acts = ten counts (in theory).
The marriage must be legally existing at the time of the act.

B. Who Can Be Charged

The married woman
The man she had intercourse with, but only if he knew she was married

If he honestly did not know (e.g., she passed herself off as single), he may have a defense.

C. Penalty

Adultery penalty: prisión correccional in its medium and maximum periods
- This roughly ranges from more than 2 years and 4 months up to 6 years of imprisonment.
Both the wife and her paramour face the same range of penalties.

IV. Concubinage

A. Definition and Modes

Under Article 334, concubinage is committed by a married man who:

Keeps a mistress in the conjugal dwelling; or
Has sexual intercourse, under scandalous circumstances, with a woman not his wife; or
Cohabits with her in any other place.

You only need one of these modes to be present.

Key concepts:

“Conjugal dwelling” – the home shared (or normally shared) by the spouses, whether owned, rented, or provided.
“Scandalous circumstances” – the affair is conducted in a way openly offensive to decency; the scandal must be clear and public, not just a private secret.
“Cohabits” – living together as if they were spouses, maintaining a relationship of some permanence.

B. Who Can Be Charged

The married man
The mistress/concubine

Both must be impleaded in the complaint, similar to adultery rules (with some qualifications).

C. Penalty

Husband: prisión correccional in its minimum and medium periods
- Roughly 6 months and 1 day up to 4 years and 2 months.
Mistress/concubine: destierro (banishment) – they are prohibited from entering certain places (e.g., the place where the offended spouse resides).

Compared to adultery, concubinage has a generally lighter penalty, which is a frequent subject of criticism.

V. Adultery vs. Concubinage: Key Differences

1. Offender’s Gender and Role

Adultery:
- Only a married woman can commit it (with her male partner).
Concubinage:
- Only a married man can commit it (with his female partner).

2. Required Acts

Adultery:
- One act of sexual intercourse with a man not her husband is enough.
Concubinage:
- The husband’s infidelity must fall into one of the specific modes:
  - Mistress in the conjugal home
  - Sex under scandalous circumstances
  - Cohabitation elsewhere

A single secret encounter in a motel, without scandal or cohabitation, often does not meet concubinage requirements (though it may be used in other types of cases like legal separation or VAWC).

3. Penalties

Adultery: Higher penalty (medium to maximum periods of prisión correccional)
Concubinage: Lower penalty (minimum to medium for the husband; destierro for mistress)

4. Degree of Proof Required

Both require proof beyond reasonable doubt, but:
- Adultery: Usually “easier” to prove if there’s direct evidence of intercourse (e.g., admission, caught in the act), though this is rare in practice.
- Concubinage: Requires proof of the mode (conjugal dwelling, scandal, or cohabitation), which can be more complicated.

VI. Who May File, Against Whom, and Special Rules

A. Only the Offended Spouse Can File

Under Article 344 RPC:

Adultery and concubinage are “private offenses.”
They cannot be prosecuted unless the offended spouse files a sworn complaint.
The prosecutor cannot start the case on his/her own, and even the police cannot file without the offended spouse’s complaint.

This means parents, siblings, or children cannot file adultery/concubinage complaints on their own.

B. The Complaint Must Include Both Parties to the Affair

In general:

For adultery: The offended husband must include both:
- his wife, and
- her paramour.
For concubinage: The offended wife must include both:
- her husband, and
- his mistress/concubine.

The rule is designed to prevent selective prosecution (e.g., charging only the mistress but not the unfaithful spouse).

If one offender has died or is beyond the court’s reach, there are some jurisprudential exceptions, but as a baseline rule, you cannot deliberately exclude one of them.

C. Consent and Pardon: When They Bar the Case

The law distinguishes between:

Consent – permission given before or as the acts are happening; and
Pardon – forgiveness given after the offense.

The case cannot be filed or continued if:

The offended spouse consented to the infidelity before or during its commission; or
The offended spouse expressly pardons both offenders (not just one) before filing the complaint.

Key nuances:

Pardon must generally be express and cover both offenders.
Sleeping on one’s rights for too long, while continuing marital relations knowingly, can sometimes be interpreted as implied pardon/condonation depending on the facts.
Pardon or condonation after filing doesn’t automatically extinguish the criminal case, but it can affect how the case proceeds and may be used as a defense or as a mitigating circumstance.

D. Prescriptive Period (Time Limit to File)

Under the rules on prescription of crimes, adultery and concubinage generally prescribe in five (5) years.
The usual reckoning point is from discovery of the offense by the offended spouse, not necessarily from the date of the act itself.

If you discover the infidelity many years after the acts, you may still file so long as the prescriptive period from discovery has not lapsed.

VII. Evidence and Practical Considerations

A. Types of Evidence Commonly Used

Typical evidence includes:

Text messages / chats / emails showing romantic or sexual relationship
Photos or videos together (especially sleeping in the same bed, PDA, etc.)
Hotel receipts, booking records, travel records showing they stayed in the same room or traveled together like a couple
Witness testimony:
- Neighbors seeing the mistress living in the conjugal home
- Co-workers or friends aware of cohabitation
Birth certificates of children born from the extramarital relationship
Admissions (oral or written) by either lover

For concubinage, you especially need proof of:

Use of the conjugal dwelling, or
Scandalous conduct (open display, public humiliation), or
Cohabitation (shared address, bills, neighbors’ testimony, etc.)

B. Legality of Obtaining Evidence

You must not commit other crimes to gather evidence, for example:

Illegal wiretapping (secretly recording private communications over phone or similar devices without consent)
Hacking or breaking into email/social media accounts without authorization
Planting recording devices in private spaces in a way that violates privacy laws

Illegally obtained evidence may be inadmissible and can even expose you to criminal liability. Always consider whether the evidence is obtained in a lawful manner.

C. Standard of Proof

As with all criminal cases, the prosecution must prove guilt beyond reasonable doubt.
Suspicion, gossip, or vague circumstantial evidence is not enough.
However, a series of strong circumstantial evidence can sometimes be sufficient if it leads logically and convincingly to only one conclusion: guilt.

VIII. Interaction with Other Legal Remedies

Marital infidelity can also be relevant in civil and family-law cases, separate from the criminal action.

A. Legal Separation

Under the Family Code, sexual infidelity is a ground for legal separation. This:

Does not dissolve the marriage (you still cannot remarry), but
Allows separation of bed and board, property relations, and decisions about custody and support.

You can file an action for legal separation even if you do not pursue criminal charges, or vice versa, or both.

B. Declaration of Nullity or Annulment

Infidelity by itself is generally not a ground for declaring a marriage void or voidable.

However:

It may be evidence of psychological incapacity (for a petition under Article 36 of the Family Code) or other grounds, depending on the facts and expert testimony.

C. Civil Actions for Damages

The offended spouse may claim moral and other damages against:

The unfaithful spouse; and
In some circumstances, the third party, especially if there was:
- Public humiliation
- Abandonment
- Harassment or intimidation

This can be done within the criminal action (as civil liability ex delicto) or through a separate civil case, depending on strategy.

D. VAWC (Republic Act No. 9262)

If the infidelity forms part of psychological or emotional abuse against a wife or a woman in an intimate relationship, it may fall under RA 9262 (Violence Against Women and their Children).

Examples:

Husband flaunting the mistress, threatening to abandon wife and children, controlling finances while living with another woman, etc.

This is different from concubinage but often overlaps factually.

IX. How to File a Case for Adultery or Concubinage

1. Decide on Your Objectives

Before filing, think about what you really want:

Punishment of offending spouse and lover?
Separation of property and support?
Custody of children?
Freedom to remarry (which requires nullity, not just criminal conviction)?

Criminal cases are emotionally draining and can take years. It’s wise to plan overall strategy (criminal, civil, and family-law actions) with a lawyer.

2. Gather and Organize Evidence

Collect documents, photos, screenshots, messages, receipts.
List potential witnesses and what they can testify about.
Write a chronology of events:
- When you married
- When you discovered the affair
- Any confrontations, admissions, acts of humiliation, etc.

3. Consult a Lawyer

Technically, you can file a complaint yourself, but in practice:

A lawyer is extremely helpful to:
- Assess if the facts fit adultery or concubinage
- Check if the prescriptive period has not lapsed
- Ensure there is no prior consent or pardon that could bar the case
- Draft a strong affidavit-complaint

4. Prepare the Affidavit-Complaint

This sworn document will be filed with the Office of the City/Provincial Prosecutor where:

The offense was committed, or
Where any of the offenders reside (depending on the rules on venue).

The affidavit-complaint should clearly state:

Your identity and your relationship to the accused (spouses)
Facts proving:
- Existence of a valid marriage
- The acts of infidelity (dates, places, circumstances)
- For adultery: that your wife had sexual intercourse with the named man
- For concubinage: that your husband committed one of the modes (mistress in conjugal home, scandalous intercourse, cohabitation)
How you discovered the offense (for prescription)
That you never consented to nor pardoned the offenders
That you are including both your spouse and the paramour/mistress as respondents, in accordance with law

Attach:

Marriage certificate
Evidence copies (screenshots, receipts, photos, etc.)
Affidavits of witnesses, if available

5. Filing with the Prosecutor

Submit the complaint and attachments to the Prosecutor’s Office with jurisdiction.
Pay any required filing fees (if applicable).
The prosecutor may:
- Require the respondents to file counter-affidavits
- Set clarificatory hearings

This is the preliminary investigation phase, where the prosecutor decides if there is probable cause to file the case in court.

6. Prosecutor’s Resolution and Filing in Court

If the prosecutor finds probable cause:

An Information will be filed in the proper trial court.
A warrant of arrest or summons may be issued, depending on the circumstances.

If the prosecutor dismisses the complaint, you typically may:

File a motion for reconsideration, and/or
Appeal to higher authorities (e.g., DOJ), within prescribed periods.

7. Arraignment, Trial, and Judgment

Once in court:

The accused will be arraigned and enter a plea (guilty/not guilty).
There will be trial, with presentation of:
- Prosecution evidence
- Defense evidence
The court then issues a judgment:
- Acquittal – case dismissed
- Conviction – penalty imposed, plus possible civil liability

X. Common Questions and Misconceptions

1. “Can I sue my husband’s mistress for adultery?”

No. Adultery applies to a married woman and her lover.

For a married man, the proper charge is concubinage, and the co-accused is his mistress/concubine. You cannot simply “switch” them.

2. “We are already separated in fact. Does that prevent an adultery/concubinage case?”

No. Separation in fact (living apart without court order) does not end the marriage. As long as the marriage is still legally valid and not legally dissolved, adultery or concubinage can still be committed.

3. “Do I need to catch them in the act?”

No, but direct evidence like that is rare. Courts accept circumstantial evidence, as long as it cumulatively proves the elements beyond reasonable doubt.

4. “If I forgive my spouse but still want to jail the mistress/paramour, is that allowed?”

Generally, no. The law requires that consent/pardon (for or against the case) cover both offenders, and you cannot choose to prosecute just one, except in narrowly defined, exceptional situations (e.g., one is already dead).

5. “Will filing a criminal case automatically allow me to remarry?”

No. Even if your spouse is convicted, your marriage remains valid until legally dissolved (e.g., by a valid declaration of nullity). Conviction for adultery/concubinage is not by itself a ground to remarry.

XI. Final Thoughts

Adultery and concubinage in the Philippines are serious criminal charges with:

Strict procedural rules (private offense, offended spouse only, both offenders joined)
Challenging evidentiary requirements
Significant emotional, financial, and social consequences for all involved

Before taking action, it’s wise to:

Reflect on your goals (punishment, separation, protection of children, financial security, emotional closure), and
Consult a Philippine lawyer experienced in criminal and family law to help you choose the right mix of criminal, civil, and family-law remedies (or alternative approaches such as mediation or purely civil actions).

If you want, you can tell me your rough factual situation (without names), and I can help map which of these remedies might fit and what issues to watch out for.