1) What these crimes are (and why they’re treated differently)

In the Philippines, adultery and concubinage are criminal offenses under the Revised Penal Code (RPC). They are not defined the same way, and they do not impose the same requirements:

Adultery (RPC Art. 333) applies to a wife who has sexual intercourse with a man not her husband, and to the male partner who knows she is married.
Concubinage (RPC Art. 334) applies to a husband who commits any of the specific acts punished by the law (not every extramarital sexual encounter qualifies), and to the female partner only in limited situations.

This asymmetry is a long-standing feature of the RPC. Courts apply the statutes as written, and the prosecution must prove the specific statutory elements beyond reasonable doubt.

2) Adultery (RPC Art. 333)

A. Who can be charged

The wife
The man who had sexual intercourse with her and knew she was married

B. Elements the prosecution must prove

To convict for adultery, it must be shown that:

The woman is married (a valid marriage existed at the time of the act); and
She had sexual intercourse with a man not her husband; and
The man knew she was married.

C. Key points about proof

The core act is sexual intercourse. Direct eyewitness proof is rare; convictions often rely on strong circumstantial evidence that leads to one fair conclusion: intercourse occurred.
The man’s liability turns on knowledge of the marriage. This can be proved by:
- admissions (messages, statements),
- circumstances (he met the husband; attended wedding; family introductions),
- the wife’s public status, living arrangements, or repeated interactions where marriage is obvious.

D. Penalty (overview)

Adultery is punished by prisión correccional in its medium and maximum periods (a correctional penalty). The precise sentence depends on circumstances and judicial discretion within the legal range.

3) Concubinage (RPC Art. 334)

Concubinage is not “any cheating by a husband.” It exists only if the husband commits any of these specific acts:

A. Acts that constitute concubinage

Any one of the following:

Keeping a mistress in the conjugal dwelling
- The “conjugal dwelling” is the marital home. Proof focuses on the mistress’s presence there as a “kept” partner, not a one-off visit.
Having sexual intercourse under scandalous circumstances
- “Scandalous” refers to circumstances that create public notoriety or disgrace, beyond private immorality. Evidence often centers on publicity, brazenness, and community awareness.
Cohabiting with her in any other place
- “Cohabitation” means living together as if husband and wife—more than occasional meetings. Think sustained, domestic life: shared residence, routines, neighbors recognizing them as a couple, etc.

B. Who can be charged

The husband
The mistress only if she falls under the law’s scope (in practice, her criminal liability is narrower than the husband’s and is tied to the specific modes described).

C. Penalty (overview)

Concubinage carries a lower penalty than adultery and may include destierro (banishment from specified places) for the female partner depending on how charged and proven. The exact imposable penalty depends on the proven mode and the court’s findings.

4) A crucial limitation: “Private crimes” and who may file (RPC Art. 344)

Adultery and concubinage are private crimes. This changes everything procedurally.

A. Only one person can start the case

Only the offended spouse (the husband in adultery; the wife in concubinage) may initiate prosecution by filing a complaint.

B. The complaint must generally include both guilty parties

As a rule, the offended spouse must file against both:

in adultery: the wife and the male partner
in concubinage: the husband and the mistress

If one party is dead, the case may proceed against the surviving accused, but if both are alive, omitting one without a legally valid reason is typically fatal.

C. Consent or pardon bars prosecution

If the offended spouse consented to the infidelity, or pardoned the offenders, criminal prosecution is barred.

Important practical notes:

Pardon can be express (written or clearly stated) or implied (conduct showing forgiveness—often argued when the couple resumes marital relations after the offended spouse learns the facts).
Timing matters. As a rule of thumb, once the case is already in motion, “forgiveness” may no longer undo what has been validly instituted, but it can still affect practical outcomes (witness cooperation, prosecutorial viability). Do not assume a later reconciliation automatically terminates the case.

5) Prescription (time limit to file)

Adultery and concubinage carry correctional penalties, and offenses punishable by correctional penalties generally prescribe in 10 years under the RPC’s prescription rules.

Two practical cautions:

The prescriptive period is typically counted from the commission of the offense (or from discovery in certain arguments depending on how the acts are framed), and
Prescription can be interrupted by filing a complaint with the proper authority.

Because venue and dates are often disputed in these cases, the safest approach is to treat timing as urgent once evidence is available.

6) Evidence: what tends to matter, what backfires, and what is risky

A. What you must prove (target facts)

Adultery:

valid marriage + intercourse + knowledge of marriage (for the man)

Concubinage:

valid marriage + one of the three statutory modes (mistress in conjugal home / scandalous intercourse / cohabitation elsewhere)

B. Commonly used evidence

Proof of marriage
- PSA marriage certificate, marriage contract/certified true copy, or other competent proof.
Hotel/short-stay evidence
- receipts, booking confirmations, guest registry entries, CCTV (if lawfully obtained), witness testimony.
Photos/videos
- showing them entering/exiting a room together, staying overnight repeatedly, affectionate behavior tied to cohabitation or scandal.
Messages and digital evidence
- chat screenshots, emails, social media messages, call logs.
- Best when supported by authentication: device extraction, metadata, testimony of the person who captured it, or other corroboration.
Proof of cohabitation (concubinage)
- lease contracts, utility bills, barangay certificates, deliveries, neighbors’ testimony, shared mail, photos of household setup, repeated overnight stays, and public presentation as a couple.
Witnesses
- hotel staff, neighbors, security guards, household helpers, friends who observed admissions or living arrangements.

C. Circumstantial evidence can be enough—if it’s strong

Courts can convict based on circumstantial evidence when:

there are multiple consistent circumstances,
they form an unbroken chain,
they lead to only one reasonable conclusion (that the required act occurred).

D. Evidence that often causes problems (privacy and admissibility)

Be careful with “DIY surveillance.” Some tactics can:

get excluded as evidence,
expose you to criminal or civil liability,
or weaken your credibility.

High-risk areas include:

Illegally recorded private conversations (wiretapping concerns),
Unauthorized access to accounts/devices (password guessing, hacking, forced phone unlocking),
Obtaining private communications through deception or intrusion,
Revenge posting or public shaming (which can trigger separate liabilities).

If digital proof is central, the strongest cases usually treat authentication and lawful acquisition as seriously as the underlying facts.

7) Where to file (venue and jurisdiction)

A. Venue rule (very important)

Criminal cases must be filed where the crime was committed.

Adultery: where the sexual intercourse took place.
Concubinage: where the relevant mode happened:
- conjugal dwelling location (if mistress kept there),
- place of scandalous intercourse,
- place of cohabitation.

Venue can be the hardest part because acts often happen privately. A complaint should allege the place with as much specificity as the evidence supports (hotel name/address, residence location, barangay/city, approximate dates).

B. Where you physically start the case

You typically begin at the Office of the City/Provincial Prosecutor with a complaint-affidavit and attachments for preliminary investigation.

8) How to file a case: step-by-step process

Step 1: Confirm you (the complainant) have standing

You must be the offended spouse:

husband files adultery complaint
wife files concubinage complaint

Also assess whether there is any consent/pardon issue that could defeat the case.

Step 2: Gather and organize evidence

Minimum practical set:

proof of marriage
timeline of events (dates, places)
proof of the specific act (intercourse / cohabitation / mistress in conjugal dwelling / scandalous circumstances)
identities and addresses of respondents (accused)
witnesses and how to contact them

Step 3: Prepare the Complaint-Affidavit

This is a sworn narrative. It should be:

chronological,
specific about places and dates (or approximate dates if exact is unknown),
tied to the legal elements,
supported by annexes.

Typical attachments (“Annexes”):

Marriage certificate
photos/videos screenshots (labeled and dated if possible)
hotel/booking documents
lease/utility proof (for cohabitation)
affidavits of witnesses (if available)
any admissions (messages), with explanation of how obtained and how authenticated

Step 4: File with the Prosecutor’s Office for Preliminary Investigation

You submit:

complaint-affidavit
supporting affidavits of witnesses (optional but helpful)
documentary/physical/digital evidence

The prosecutor will:

require the respondents to submit counter-affidavits,
evaluate probable cause,
issue a resolution recommending filing in court or dismissal.

Step 5: If probable cause is found, the Information is filed in court

Once filed:

the court may issue a warrant or summons depending on circumstances,
the case proceeds to arraignment, pre-trial, and trial.

Step 6: Trial (proof beyond reasonable doubt)

At trial the burden is high. Expect:

challenges to authenticity of photos/chats,
defenses attacking venue and dates,
arguments that evidence shows “suspicious circumstances” but not the specific legal act (especially for concubinage).

9) Common defenses and case killers

A. For both crimes

No valid marriage at the time (void marriage issues can become complicated; the criminal court may look at presumptions and records, but marital validity disputes can derail certainty).
Improper party filed (not the offended spouse).
Failure to include both accused when both are alive and should be charged together.
Pardon/consent (express or implied).
Wrong venue or inability to prove the act occurred within the court’s jurisdiction.
Insufficient proof of the specific statutory act.

B. Specific to adultery

Cannot prove sexual intercourse (mere intimacy, dates, or cohabitation suspicions may be argued as insufficient).
Cannot prove the man’s knowledge of the woman’s marriage.

C. Specific to concubinage

Proof shows “affair” but not any of the three statutory modes.
“Cohabitation” not shown (occasional meetups ≠ cohabitation).
“Scandalous circumstances” not established (private acts with no notoriety).

10) Relationship to civil cases (legal separation, annulment, support)

Criminal prosecution is separate from civil remedies, but the same factual events often overlap with:

Legal separation (infidelity is a recognized ground in Philippine family law, subject to its own requirements and defenses such as condonation).
Annulment/nullity (infidelity is not itself a ground for nullity, but may be relevant to other issues like psychological incapacity claims in some pleadings).
Support, custody, property disputes (often triggered by marital breakdown; these are governed by family law rules, not criminal standards).

A criminal case requires proof beyond reasonable doubt; many civil actions proceed on lower standards of proof and different elements.

11) Practical drafting guide: what prosecutors look for in a strong complaint-affidavit

A complaint-affidavit tends to be stronger when it contains:

Parties section: full names, ages, civil status, addresses; proof that complainant is the offended spouse.
Marriage proof: attach certificate and state date/place of marriage.
Clear theory of the crime:
- Adultery: “intercourse occurred at X place on/around Y date; respondent male knew she was married because…”
- Concubinage: specify which mode applies and facts proving it (cohabitation, conjugal dwelling, or scandal).
Venue facts: why the offense is within the city/province.
Evidence map: each annex tied to a factual claim.
Witness list: who will testify to which facts.
Relief: request for finding of probable cause and filing of Information.

12) Summary checklist

Adultery:

✅ offended husband files
✅ charge wife + male partner (if both alive)
✅ prove marriage + intercourse + man’s knowledge
✅ file where intercourse occurred

Concubinage:

✅ offended wife files
✅ charge husband + mistress (if both alive)
✅ prove marriage + one of three modes
✅ file where conjugal dwelling/cohabitation/scandalous intercourse occurred

For both:

✅ watch out for consent/pardon/condonation arguments
✅ ensure evidence was lawfully obtained and can be authenticated
✅ venue and specificity often decide whether a case survives early dismissal