This article explains, in plain but precise terms, how these cases work in Philippine law—from elements and evidence to filing steps, defenses, timelines, and practical pitfalls. It’s written for spouses considering legal action and for counselors or paralegals who need a single, comprehensive reference.

1) The Legal Groundwork

Governing provisions

Adultery is punished under Article 333 of the Revised Penal Code (RPC). Elements: (a) the woman is married, (b) she had sexual intercourse with a man not her husband, and (c) the act happened during the marriage.
Concubinage is punished under Article 334 RPC. Elements (any of the three is enough): (a) the husband keeps a mistress in the conjugal dwelling; or (b) he has sexual intercourse under scandalous circumstances with a woman not his wife; or (c) he cohabits with her in any other place.

Who may file (private crimes)

These are private crimes. Only the offended spouse may initiate the criminal process by filing a sworn complaint. Without this complaint, prosecutors and courts have no jurisdiction.
The complaint must include both offenders:
- For adultery: the wife and her paramour.
- For concubinage: the husband and the mistress. Failure to implead both (if living and known) is a fatal defect.

Valid marriage required

There must be a valid, subsisting marriage at the time of the alleged act. A marriage later declared void generally bars these crimes (because there was never a valid marriage). A voidable marriage is valid until annulled; acts before annulment can still qualify.

Penalties (for perspective)

Adultery: wife and paramour—prisión correccional in its medium and maximum periods (i.e., 2 years, 4 months and 1 day to 6 years).
Concubinage: husband—prisión correccional in its minimum and medium periods (i.e., 6 months and 1 day to 4 years and 2 months); mistress—destierro (banishment from specified places).

Practical takeaway: penalties exceed one year, so barangay conciliation is not a prerequisite to filing.

Consent and pardon (bars to prosecution)

Prior consent (agreeing beforehand) or subsequent pardon (forgiveness before filing) by the offended spouse bars the case.
Pardon/consent must cover both offenders and occur before filing. Implied pardon can arise from conduct clearly showing acquiescence (e.g., resuming marital relations with full knowledge, depending on facts).

Each act vs. continuing offense

Adultery: each act of sexual intercourse is a separate offense.
Concubinage: “keeping a mistress in the conjugal home” and “cohabiting elsewhere” are continuing in nature; “scandalous intercourse” may be charged per episode if the facts fit.

Prescription

These are correctional offenses; the general rule is a 10-year prescriptive period. For practical purposes, computation commonly runs from discovery of the offense by the offended spouse (or authorities), but consult counsel on exact reckoning because prescription rules can be fact-sensitive.

2) Evidence: What You Need and How to Gather It Lawfully

Burden and standard

The State must prove guilt beyond reasonable doubt. Direct proof of sexual intercourse is not strictly required; credible circumstantial evidence can suffice (e.g., consistent eyewitness accounts + hotel receipts + chat logs showing intimacy and opportunity).

Typical proof packets

Identity and status
- PSA-certified Marriage Certificate (and Advisory on Marriages if helpful).
- Birth certificates of children (only if relevant to motive, timelines, or support issues).
Acts and opportunity
- Photos/videos clearly identifying the parties (time/location metadata helps).
- Receipts/records: hotel/condo logs, booking confirmations, lease contract showing cohabitation.
- Witness statements: neighbors, building staff, friends who saw cohabitation or scandalous acts.
- Digital communications: emails, messages, posts, or public comments showing the relationship and circumstances.
Cohabitation/Conjugal dwelling
- Barangay certifications, homeowner/condo admin letters, utility bills, deliveries addressed to the pair.
- Proof of maintenance/support of the mistress (bank transfers, allowance notes).

Evidence you should not obtain illegally

Wiretapped audio or secretly recorded phone calls without all-party consent may violate the Anti-Wiretapping Act (RA 4200)—generally inadmissible and may expose you to liability.
Hacked accounts or unlawfully accessed private data are also risky. Stick to lawful, voluntarily obtained, or public-facing materials, and seek counsel before submitting sensitive digital evidence.

3) Step-by-Step: How to File

Step 1: Decide your overall strategy

Criminal filing can be paired with:
- Legal Separation (ground: sexual infidelity), or
- Nullity/Annulment (if legally supportable), and/or
- Civil claims for damages within the criminal action (moral, exemplary, attorney’s fees). Coordinate sequences to avoid inconsistent positions and to maximize protection (e.g., support, custody, property).

Step 2: Prepare the Sworn Complaint-Affidavit

Include:

Your identity and proof of marriage.
Complete names and identifying details of both offenders (spouse and paramour/mistress).
Narrative of facts with dates, places, and elements ticked off (e.g., “kept a mistress in the conjugal home at [address] from [date] to [date]”).
List of evidence and witnesses.
Statement that you have not consented or pardoned the acts and that the offenders are alive and known (or explain if deceased/unknown).
Prayer for their prosecution and civil liability.

Attach certified copies where applicable and label exhibits clearly (A, B, C…).

Step 3: File with the Office of the City/Provincial Prosecutor

Venue: where any essential element occurred (e.g., city of cohabitation, conjugal home, scandalous act, or sexual intercourse). If multiple locales, choose the most fact-dense and convenient.
Pay the small filing fee (if any) and obtain acknowledgment.

Step 4: Preliminary Investigation

The prosecutor issues a subpoena to both respondents with copies of your complaint and annexes.
Counter-affidavits (with annexes) are filed; reply/rejoinder rounds may follow.
The prosecutor may hold clarificatory hearings.
After evaluation, the prosecutor issues a Resolution:
- File Information (sufficient cause) → case goes to the trial court; or
- Dismiss the complaint (insufficient cause).

Step 5: If Information is filed

Case is raffled to the Regional Trial Court (RTC) with criminal jurisdiction.
Arraignment, pre-trial, trial on the merits follow.
You may present civil claims within the criminal case (no need for a separate civil suit unless you prefer to reserve it).
Offenses are bailable. The court may issue Warrants of Arrest; respondents may post bail.

4) Building a Strong Case

Checklists by offense

Adultery (against wife & paramour)

PSA Marriage Certificate proves a valid marriage when acts occurred.
Dates/places of sexual intercourse identified as specifically as possible.
Corroboration: hotel/booking receipts, security logs, photos together at times consistent with intimacy, admissions in chats.
No prior consent/pardon—address this expressly.
Both offenders impleaded.

Concubinage (against husband & mistress)

Plead at least one of the three modes and prove it:
- Mistress kept in conjugal dwelling (address, neighbors, deliveries, access devices).
- Scandalous intercourse (publicity, notoriety, setting showing public offense).
- Cohabitation elsewhere (lease, bills, admin certifications).
Pattern/continuity for cohabitation; dates spanning an interval.
No prior consent/pardon.
Both offenders impleaded.

Practical evidence tips

Gather consistent circumstantial strands: presence + opportunity + intimacy + continuity.
Time-stamp your evidence; preserve originals and metadata.
Use affidavits of neighbors/building staff to establish cohabitation or scandal.
Be cautious with private data; when in doubt, consult counsel before filing.

5) Common Defenses You’ll Face (and How They Work)

Invalid marriage (void ab initio) → complete defense.
Prior consent or pardon by offended spouse → bars prosecution.
Prescription (too late) → may defeat the case.
Failure to implead both offenders (jurisdictional in private crimes) → dismissal.
Alibi/denial → counter with credible, consistent circumstantial evidence and documents.
Lack of “scandalous circumstances” (for that concubinage mode) → be ready with facts showing public offensiveness or notoriety.
No cohabitation (they’ll claim “sporadic meetings”) → emphasize continuity: shared address, bills, admin notices, neighbor testimony.

6) Civil, Family, and Protective Remedies You Can Pair or Sequence

Legal Separation on the ground of sexual infidelity → effects on property relations, succession, and use of surnames.
Nullity/Annulment (if legally available) → resolves status, custody, and property; also affects whether the criminal case is viable for past acts.
Damages within the criminal case (moral, exemplary, attorney’s fees).
Support and custody proceedings for children.
Protection orders (if there is abuse qualifying under special laws such as RA 9262).

Coordinate filings carefully—actions in family court may influence strategies and timelines in the criminal case.

7) Timelines, Costs, and Risks

Preliminary investigation can run several weeks to months depending on docket load.
Trial may take longer, especially with multiple incidents (adultery) or wide evidence (concubinage).
Costs: filing is modest, but certifications, document procurement, lawyer’s fees, and expert witness costs add up.
Emotional and social impact: these cases are public records and can be stressful for families and children—plan for support systems.

8) Ethical and Safety Considerations

Avoid self-help surveillance that breaks the law (e.g., secret call recordings).
Secure your own digital accounts and devices; change passwords if needed.
Consider counseling or mediation for parallel family issues, even while preserving rights.

9) Frequently Asked Practical Questions

Q1: Do I need to confront them first? No. There is no legal requirement to confront. Many lawyers discourage confrontation to avoid evidence spoliation or implied pardon.

Q2: Can I file in the barangay first? Not required—the penalties exceed one year.

Q3: What if I forgave them before, but I’ve changed my mind now? A valid prior pardon/consent generally bars prosecution, even if you later regret it. Facts matter; consult counsel.

Q4: We live apart—does concubinage still apply? Yes, if you can prove cohabitation elsewhere or scandalous intercourse. If none of the three modes fits, the case may not prosper.

Q5: What if the paramour/mistress is unknown? Explain this in your complaint. If identity becomes known, amend to implead them. Courts are strict about the “both offenders” rule.

Q6: Can I also sue for damages separately? You can claim civil liability in the criminal case or reserve your right to file a separate civil action—but coordinate strategy to avoid waivers or duplications.

10) Model Complaint-Affidavit Outline (For Reference)

Title/Caption (People of the Philippines vs. [Spouse] and [Paramour/Mistress])
Affiant’s Personal Details
Jurisdiction & Venue Allegations
Existence of Valid Marriage (attach PSA Marriage Certificate)
Material Facts establishing each element (dates, places, acts)
Evidence Summary (attach copies, list witnesses)
No Consent/Pardon Statement
Prayer (criminal prosecution and civil liability)
Verification and Sworn Statement (jurat)

Tip: Put a one-page “Elements Table” in your annexes mapping each legal element to specific exhibits.

11) Final Pointers Before You File

Precision beats volume. Curate a tight, credible evidence set that directly proves elements.
Mind the clock. Consider prescription and gather proof of date of discovery.
Name both respondents. Double-check spellings and identifying details.
Protect your children and property interests through parallel family court remedies.
Get counsel early. A short consult can save months of missteps (e.g., on venue, prescription, and admissibility).

Disclaimer

This article provides general legal information on Philippine law for educational purposes and is not a substitute for tailored advice from a Philippine lawyer. Facts, timelines, and documents materially affect outcomes.