1) The Legal Framework (Why These Cases Work Differently)

In the Philippines, adultery and concubinage are crimes under the Revised Penal Code (RPC). They are commonly called “private crimes” because prosecution generally cannot start on the initiative of the State alone—it requires a sworn complaint by the offended spouse and is subject to unique rules that do not apply to most crimes.

Key provisions:

RPC Article 333 — Adultery
RPC Article 334 — Concubinage
RPC Article 344 — Prosecution rules (private-complaint requirement, inclusion of both guilty parties, pardon/consent as a bar)

Because these are criminal cases, the standard at trial is proof beyond reasonable doubt. But to start and move a case forward (during the prosecutor’s evaluation/preliminary investigation), you typically need evidence sufficient to show probable cause—that it is more likely than not that the crime was committed and the respondents probably committed it.

2) Adultery (RPC Art. 333)

A. What it is (Definition)

Adultery is committed when:

A married woman has sexual intercourse with a man not her husband, and
The man knows she is married (knowledge is usually inferred when circumstances show he was aware).

Important: The crime is about sexual intercourse. Emotional affairs, flirting, dates, gifts, chat intimacy, and staying close—by themselves—are not adultery unless they convincingly prove intercourse occurred.

B. Who can file (Standing / Proper complainant)

Only the offended spouse—the husband of the married woman—can file the sworn complaint required to prosecute adultery.

Practical implications:

Parents, siblings, children, friends cannot file in their own names.
The husband generally must be the one to execute/verify the complaint (through counsel is fine, but the complainant is still the husband).
If the offended spouse dies before filing, the case generally cannot be initiated; if death happens after a proper case has started, the criminal action may proceed.

C. Mandatory inclusion of both guilty parties

A hallmark rule under Article 344:

The husband cannot file adultery against only the wife or only the paramour.
The complaint must include both the wife and the man (if both are alive and identifiable).

This often becomes a practical hurdle: if the husband can’t identify the paramour with reasonable specificity, the case is difficult to pursue.

D. Consent, pardon, and reconciliation (Bars to prosecution)

Prosecution is barred if the offended spouse has consented to the adultery or has pardoned the offenders.

Common real-world forms (often litigated):

Express pardon (written or clearly stated forgiveness)
Implied pardon/condonation (for example, continuing marital cohabitation after learning of the affair, in a way that clearly signals forgiveness—this is fact-sensitive and not automatic)

Because these rules can end a case even when infidelity is real, the timeline of when the spouse learned, what they did after learning, and what communications occurred can matter as much as proof of the affair itself.

3) Concubinage (RPC Art. 334)

A. What it is (Definition)

Concubinage is committed by a married man who does any of the following:

Keeps a mistress in the conjugal dwelling, or
Has sexual intercourse with a woman under scandalous circumstances, or
Cohabits with her in any other place.

It is not enough that the husband is merely unfaithful. The law requires one of the three qualifying modes.

B. Who can file

Only the offended spouse—the wife of the married man—can file the sworn complaint for concubinage.

Same practical rules apply:

No one else can initiate the case in their own name.
The complaint must typically be sworn/verified by the offended wife.

C. Mandatory inclusion of both parties

Like adultery, Article 344 generally requires inclusion of:

The husband, and
The concubine/mistress (assuming both are alive and can be identified)

D. Consent and pardon

Concubinage prosecution is also barred by consent or pardon by the offended wife, subject to the same fact-sensitive issues as adultery.

4) What Must Be Proven (Elements and Evidence)

A. Evidence needed in both crimes (baseline)

Whether adultery or concubinage, these are typically the baseline proof points:

A valid marriage exists
- Usually proven through a marriage certificate (PSA copy) and/or testimony.
Identity of the respondents
- Correct names, addresses, and other identifiers.
The specific criminal act
- For adultery: sexual intercourse
- For concubinage: one of the three qualifying modes

Because direct proof of intercourse is rare, these cases often rise or fall on strong circumstantial evidence—but it must be more than suspicion.

B. Adultery: What evidence proves “sexual intercourse”?

Courts rarely get “eyewitness” testimony of the act itself. Proof is commonly built from a pattern of facts showing opportunity + intimacy + circumstances inconsistent with innocence.

Examples of evidence commonly used (depending on legality and admissibility):

Hotel or lodging evidence
- Receipts, bookings, check-in logs, room assignments, CCTV showing both entering the same room and staying overnight, staff affidavits.
Witness testimony
- Witnesses who saw the pair repeatedly entering/leaving a private place at late hours, staying overnight, or behaving like a couple in a way tied to a specific time and place.
Admissions
- Messages or statements like “I’m pregnant with your child,” “we slept together,” “last night,” etc.
Pregnancy/child evidence
- Pregnancy can support inferences, but paternity still matters; admissions or strong corroboration helps. DNA evidence may arise in related proceedings.
Photographs/videos
- Not mere sweet photos. The stronger they show intimate circumstances connected to a private place/time, the more probative.

What usually is not enough by itself:

Purely romantic chats without concrete sexual admissions
Jealousy-based conclusions
“They were seen together in public” (without more)
Rumors, hearsay, anonymous tips

C. Concubinage: Evidence depends on the mode alleged

Mode 1: “Keeping a mistress in the conjugal dwelling”

You must show:

The place is the conjugal dwelling (the spouses’ marital home), and
The mistress is being kept there (living there, staying there as a maintained partner, not merely visiting once).

Evidence may include:

Barangay/HOA records, guard logs, neighbor affidavits
Utility bills, deliveries, keys/access, personal belongings in the home
Photos/CCTV showing routine entry, overnight stays, moving in
Written admissions

Mode 2: “Sexual intercourse under scandalous circumstances”

This requires two things:

Sexual intercourse, and
The circumstances are scandalous—i.e., open and notorious enough to offend public morals or cause public outrage (more than ordinary secrecy).

Evidence may include:

Public cohabitation-like behavior that is widely known in the community
Repeated public displays plus community notoriety
Proof the relationship is carried on in a way that creates a public scandal (fact-specific)

This is often the hardest mode because “scandalous circumstances” is not automatically present just because cheating exists.

Mode 3: “Cohabiting with her in any other place”

This is commonly alleged and litigated.

You must show:

They live together in another residence (not necessarily permanently, but with the character of living as partners).

Evidence may include:

Lease contracts, shared bills, shared address usage
Neighbor/landlord testimony
Deliveries, mail, documented overnights over time
Photos/CCTV consistent with living together
Social media posts showing a shared home setup
Admissions in messages (“our place,” “our house,” “I moved in,” etc.)

What is usually not enough:

Occasional meetups
Visiting a place repeatedly without proof of living together
“Traveling together” without proof of cohabitation

5) Who Can File, Exactly, and What the Complaint Must Look Like

A. The complainant must be the offended spouse

Adultery: offended husband
Concubinage: offended wife

B. The complaint must be sworn/verified

A proper initiation typically requires:

A Complaint-Affidavit (sworn)
A narration of specific facts: dates (approximate if needed), places, acts, identity details
Attachments: documents and other evidence
Witness affidavits (if any)

C. Both respondents must be charged together

As a rule, the offended spouse cannot “choose only one” respondent to prosecute if both are alive and identifiable.

D. Venue (where to file)

Criminal cases are generally filed where:

The adulterous acts occurred (adultery), or
The conjugal dwelling is located / cohabitation occurs / scandalous acts occurred (concubinage)

If the acts span multiple places, each act or continuing conduct can affect venue and the number of charges.

6) Procedure in Practice (From Filing to Trial)

While details vary by locality and case posture, the typical path is:

Preparation of complaint-affidavit by the offended spouse (usually with counsel)
Filing with the Office of the City/Provincial Prosecutor (common route)
Evaluation / Preliminary investigation (especially when the imposable penalty triggers it; in practice prosecutors often still require counter-affidavits and conduct evaluation even in lower-penalty cases)
Resolution (dismissal or filing of an Information in court)
Court proceedings: arraignment, pre-trial, trial, judgment

Because these are bailable offenses, respondents are typically entitled to bail (subject to the applicable rules and stage of the case).

7) The Most Common Evidence Problems (And How Cases Collapse)

A. Illegally obtained recordings (Anti-Wiretapping risk)

Recording a private phone call or intercepting private communications without consent can expose a complainant to criminal liability and can make evidence inadmissible.

B. Private sexual images (Voyeurism and privacy risks)

Recording or sharing intimate acts/images can violate the Anti-Photo and Video Voyeurism Act and related privacy laws—often creating bigger legal exposure than the adultery/concubinage case itself.

C. Hacking and account intrusion

Accessing someone’s phone, email, or social media without authority can lead to criminal and civil liability. Evidence obtained this way is risky and may be excluded or trigger countercharges.

D. Weak circumstantial evidence

Courts require that circumstantial evidence forms a coherent chain pointing to guilt beyond reasonable doubt. Many complaints rely on:

Screenshots with no authentication,
Hearsay (“my friend told me…”),
Inferences from mere friendliness,
Suspicion without time/place specifics.

8) Electronic Evidence (Texts, Chats, Social Media): What Makes It Strong

Electronic proof is often central, but it must be authenticated.

Best practices (conceptually):

Preserve messages with context: dates, participant identities, full threads (not cropped snippets).
Show linkage to the respondent (account ownership, phone number, profile identity, corroborating photos, admissions).
Support screenshots with:
- Testimony from the person who captured them,
- Device identification,
- Other corroboration (hotel receipts, witness accounts, travel records).
Avoid editing, altering, or selectively stitching fragments.

Even strong chats often prove only romance—unless they contain concrete admissions or are corroborated by real-world proof (overnights, shared residence, etc.).

9) Defenses and Legal Bars Commonly Raised

Respondents often challenge cases through:

No valid marriage (or marriage not adequately proven)
No sexual intercourse / no qualifying concubinage mode
Mistaken identity / wrong respondent
No “scandalous circumstances” (concubinage mode 2)
No cohabitation (concubinage mode 3)
Pardon/condonation/consent by offended spouse
Defective complaint (not properly sworn, not filed by offended spouse)
Failure to include both guilty parties
Prescription (time-bar)
Wrong venue / lack of jurisdiction
Insufficiency of evidence at probable cause stage or trial

10) Penalties (Why Adultery and Concubinage Feel “Unequal”)

The RPC treats these differently:

Adultery

Wife and paramour: prisión correccional (medium to maximum)

Concubinage

Husband: prisión correccional (minimum to medium)
Concubine: destierro (banishment/restriction from specified places)

This difference is frequently criticized as gendered and asymmetrical, but it remains part of the codal law.

11) Related (Non-Criminal) Consequences People Often Overlook

Even when someone chooses not to file (or cannot sustain) a criminal case, the same facts can matter in:

Legal separation proceedings (sexual infidelity is a ground)
Nullity/annulment-related litigation (depending on the theory and evidence)
Child custody and parental fitness considerations (always best interest of the child)
Support and property disputes
Disqualification issues under civil law concepts (e.g., effects on donations or succession in certain situations, depending on facts)

These are separate from criminal prosecution and have different standards and objectives.

12) Practical Evidence Checklist (What a Strong Case Usually Has)

For both crimes

PSA marriage certificate
Clear identity details of both respondents
A timeline (dates, places, frequency)
At least one of:
- Hotel/lodging proofs
- Proof of shared residence/cohabitation
- Witness affidavits with specific observations
- Clear admissions in authenticated communications
- Other corroborating documents (travel records, bills, leases)

Plus, depending on the charge

Adultery: proof pointing to sexual intercourse
Concubinage: proof fitting one specific mode (conjugal dwelling / scandal / cohabitation)

Key Takeaways

Only the offended spouse can file: husband for adultery; wife for concubinage.
A sworn complaint is required, and it generally must name both guilty parties.
The decisive issue is rarely “Is there an affair?” but “Can you prove the legally required act?”
- Adultery: sexual intercourse
- Concubinage: one of three qualifying modes
Strong, lawful, corroborated evidence is the difference between dismissal at probable cause and a case that can survive trial.