In the Philippines, where divorce remains legally unavailable for most citizens, Annulment and Declaration of Nullity of Marriage serve as the primary legal avenues to dissolve or invalidate a marital union. While often used interchangeably in casual conversation, they are distinct legal concepts under the Family Code of the Philippines.

1. Annulment vs. Declaration of Nullity

Before diving into the grounds, it is crucial to distinguish between a "void" marriage and a "voidable" marriage.

Declaration of Nullity (Void Marriages): This applies to marriages that were invalid from the very beginning (ab initio). In the eyes of the law, the marriage never existed.
Annulment (Voidable Marriages): This applies to marriages that are considered valid until they are set aside by a court decree. There is a "defect" at the time of the celebration that allows one party to terminate the union.

2. Common Grounds for Annulment (Article 45)

Under the Family Code, a marriage may be annulled for any of the following causes existing at the time of the marriage:

Lack of Parental Consent: If either party was between 18 and 21 years old and the marriage was solemnized without the consent of parents or guardians (unless the party freely cohabited after reaching 21).
Insanity: If either party was of unsound mind at the time of the marriage.
Fraud: This includes non-disclosure of a prior conviction involving moral turpitude, concealment of pregnancy by another man, or concealment of a sexually transmitted disease or drug addiction.
Force, Intimidation, or Undue Influence: If the consent of either party was obtained through external pressure or threats.
Physical Incapacity: If either party is physically incapable of consummating the marriage (impotence) and such incapacity appears to be incurable.
Serious and Incurable Sexually Transmitted Disease (STD): If either party was found to have a serious and incurable STD.

3. Psychological Incapacity (Article 36)

The most frequently cited ground in Philippine courts is Article 36, which covers Psychological Incapacity. Technically, this falls under a "Declaration of Nullity" rather than an annulment.

It refers to a party's inability to comply with the essential marital obligations (e.g., mutual love, respect, support, and fidelity) due to a psychological condition. Following the landmark ruling in Tan-Andal v. Andal, the Supreme Court clarified that psychological incapacity:

Does not need to be a clinical illness.
Does not require an expert medical witness (though it is still highly recommended).
Must be legal in nature, showing a profound lack of cognitive and volitional capacity to fulfill marriage duties.

4. The Legal Procedure: Step-by-Step

I. Preparation and Filing

Legal Counsel: The petitioner must hire a lawyer to draft and file a verified Petition for Annulment or Declaration of Nullity in the Family Court of the province or city where either the petitioner or respondent has been residing for at least six months.
Psychological Evaluation: In cases involving Article 36, the petitioner usually undergoes evaluation by a clinical psychologist or psychiatrist to establish the gravity and antecedents of the incapacity.

II. Summoning the Respondent

The court issues a summons to the other spouse (the respondent). If the respondent cannot be located, service by publication may be permitted.

III. Investigation for Collusion

To prevent "quickie" or "agreed-upon" annulments, the court tasks the Public Prosecutor (Office of the Solicitor General) to investigate whether collusion exists between the parties. If the prosecutor finds that the parties fabricated the grounds together, the case will be dismissed.

IV. Pre-Trial and Trial

Pre-Trial: The parties meet to simplify issues and establish facts.
Trial: This is the evidentiary stage where the petitioner, witnesses (family, friends), and experts (psychologists) testify. Cross-examination by the respondent’s counsel and the Public Prosecutor occurs here.

V. Judgment and Registration

If the judge finds sufficient evidence, a Decision is issued. After the 15-day reglementary period (if no motion for reconsideration is filed), the court issues a Certificate of Finality.

Liquidation of Assets: The court will also rule on the partition of properties and the custody and support of children.
Registration: The decree must be registered with the Local Civil Registrar where the marriage was recorded and the Civil Registrar General (PSA).

5. Important Considerations

Cost: Legal fees, psychological evaluations, and filing fees can be substantial. Total costs often range from PHP 200,000 to PHP 500,000 or more, depending on complexity.
Timeline: There is no "fast track." Depending on the court's docket and the complexity of the case, the process typically takes 2 to 4 years.
Prescription Period: For most voidable marriages (Annulment), the petition must be filed within five years of the occurrence of the ground (e.g., five years after reaching age 21 for lack of parental consent). Cases for Article 36 (Nullity) do not expire.

Comparison Table: Void vs. Voidable Marriages

Feature	Declaration of Nullity (Void)	Annulment (Voidable)
Status	Never valid from the start.	Valid until annulled.
Common Grounds	Article 36, Bigamy, Lack of License.	Fraud, Force, Impotence, Insanity.
Prescription	Does not expire (Imprescriptible).	Generally 5 years.
Children's Status	Usually "Illegitimate" (except Art. 36/53).	"Legitimate" if conceived before decree.