In the Philippines, where a general divorce law remains absent for non-Muslim citizens, the legal termination of a marriage is primarily governed by the Family Code of the Philippines. Legal practitioners and the public often use "annulment" as a catch-all term, but Philippine law strictly distinguishes between an Annulment (of a voidable marriage) and a Declaration of Absolute Nullity (of a void marriage).

I. Understanding the Legal Distinction

The grounds, procedures, and legal status of the parties depend entirely on whether the marriage is considered void or voidable.

1. Declaration of Absolute Nullity (Void Marriages)

A void marriage is considered non-existent from the beginning (void ab initio). It is as if the marriage never took place.

Common Grounds (Articles 35, 36, 37, 38):
- Psychological Incapacity (Article 36): The most frequently cited ground. It refers to a party's inability to comply with the essential marital obligations (procreation, mutual help, support, fidelity) due to a psychological condition existing at the time of the celebration.
- Absence of Requisites: Lack of a valid marriage license or a person authorized to solemnize the marriage.
- Bigamous or Polygamous Marriages: Marrying while a previous marriage is still subsisting.
- Incestuous Marriages: Between ascendants and descendants, or siblings.
- Public Policy: Marriages between first cousins or collateral relatives up to the fourth civil degree.
Prescriptive Period: An action for the declaration of absolute nullity does not prescribe; it can be filed at any time.

2. Annulment (Voidable Marriages)

A voidable marriage is considered valid until it is set aside by a court decree.

Common Grounds (Article 45):
- Lack of Parental Consent: If a party was between 18 and 21 and married without parental consent (unless they continued to cohabit after reaching 21).
- Insanity: One party was of unsound mind at the time of marriage.
- Fraud: Obtaining consent through concealment of pregnancy by another man, sexually transmitted diseases, drug addiction, or criminal records.
- Force, Intimidation, or Undue Influence.
- Physical Incapacity: Inability to consummate the marriage (impotence) that appears to be incurable.
Prescriptive Period: Generally five years from the discovery of the ground or the cessation of the force/intimidation.

II. The Procedural Roadmap

The process is a judicial one, requiring a full trial before a Regional Trial Court (RTC) designated as a Family Court.

1. Filing the Petition

The process begins with the filing of a verified Petition for Annulment or Declaration of Nullity in the province or city where the petitioner or the respondent has resided for at least six months prior to the filing.

2. Summons and Answer

The court issues a summons to the respondent. If the respondent cannot be located, service by publication may be allowed. The respondent has 15 days (or 30 days if served by publication) to file an Answer.

3. Investigation by the Public Prosecutor

Since the State has an interest in protecting the "inviolable social institution" of marriage, the court orders the Public Prosecutor (Fiscal) to conduct an investigation. The goal is to ensure there is no collusion between the parties (i.e., they aren't just "agreeing" to end the marriage without valid legal grounds).

4. Pre-Trial and Trial

Pre-Trial: The parties meet to simplify issues and mark evidence.
Trial: The petitioner must present evidence. In Article 36 cases, this usually includes testimony from a Clinical Psychologist or Psychiatrist who has evaluated the parties and can testify to the gravity, juridical antecedence, and incurability of the psychological incapacity.

5. The Decree

If the court is satisfied that the grounds have been proven, it will issue a Decision granting the annulment or nullity. This is followed by a Decree of Annulment/Nullity once the decision becomes final and executory.

III. Legal Consequences

A court decree does more than just change civil status; it addresses the "incidents" of the marriage:

Status of Children: Children of marriages declared void under Article 36 (Psychological Incapacity) are considered legitimate. In other void marriages, children are generally considered illegitimate unless the law specifies otherwise.
Property Relations: The court will order the liquidation, partition, and distribution of the properties of the spouses. For void marriages, the rules of Co-ownership usually apply.
Custody and Support: The court will determine child custody based on the "Best Interest of the Child" rule and order appropriate financial support.
Right to Remarry: The parties can only remarry once the Decree is registered with the Local Civil Registrar and the Philippine Statistics Authority (PSA).

IV. Important Considerations

Timeline: The process is notoriously lengthy, often taking anywhere from 1.5 to 4 years, depending on the court's docket and the complexity of the case.
Cost: Significant expenses include attorney’s fees, psychological evaluation fees, filing fees, and costs for publication (if required).
Strict Standards: While the Supreme Court (notably in Tan-Andal v. Andal) has relaxed the "medical" requirement for psychological incapacity, it still requires "clear and convincing evidence" to prove that the incapacity is enduring and prevents the fulfillment of marital duties.