Under the Philippine Family Code, voidable marriages are those which may be annulled or declared voidable due to specific legal grounds, as opposed to void marriages, which are invalid from the beginning. The key distinction is that voidable marriages are initially valid until annulled by a competent court. Defenses in annulment cases focus on factors that may either prevent annulment or preserve the marriage's validity. Here's an in-depth discussion on voidable marriages and defenses under Philippine Civil Law:

1. Grounds for Voidable Marriages (Article 45, Family Code)

Voidable marriages are those that can be annulled due to certain conditions or factors that affect consent or capacity at the time of the marriage. The grounds include:

Lack of Parental Consent: If one of the parties is between 18 and 21 years of age, marriage requires parental consent. Absence of this consent can be a ground for annulment.
Insanity: If one party was insane at the time of the marriage, it is grounds for annulment unless the insane person, after regaining sanity, freely cohabited with the other.
Fraud: Fraudulent acts that directly affect consent, such as non-disclosure of a criminal conviction or pregnancy by another man, can render the marriage voidable.
Force, Intimidation, or Undue Influence: If either party was forced or unduly influenced into marriage, it can be annulled if they didn’t willingly cohabit after the removal of such force.
Impotence or Physical Incapacity: When a spouse is physically incapable of consummating the marriage and this incapacity appears to be incurable, the marriage may be annulled.
Sexually Transmitted Disease: If, at the time of marriage, one party was afflicted with a sexually transmitted disease that appears incurable, annulment is possible.

Each of these grounds has specific requirements that must be proven in court, making annulment a fact-intensive process.

2. Defenses to Annulment of Voidable Marriages

The defenses against annulment of voidable marriages typically aim to demonstrate that one or more statutory requirements have not been met. These defenses include:

Ratification by Cohabitation: According to Article 45, some grounds for annulment become nullified if the affected party cohabits freely with the other after the removal of the impediment. For instance:
- In cases of insanity, if the insane spouse, after regaining sanity, freely cohabits with the other spouse, the right to annulment is waived.
- In cases involving fraud, force, or intimidation, if the aggrieved party continues to live with the spouse after discovering the fraud or after force/intimidation ceases, the right to annul the marriage is extinguished.
Waiver or Laches: If the affected party delays unreasonably in filing for annulment after the impediment is removed or discovered, a defense of laches (undue delay) can bar the annulment. This applies particularly where the delay indicates an implied waiver.
Estoppel: If the spouse seeking annulment has conducted themselves in a way that induced the other to believe the marriage is valid, and the other party has relied upon this to their detriment, the court may deny annulment based on estoppel.
Absence of Specific Grounds: It is not enough for the petitioner to simply allege unhappiness or incompatibility. If none of the enumerated grounds for voidable marriage under Article 45 are proven, the marriage cannot be annulled.
Statute of Limitations: Article 47 of the Family Code specifies a time limit for filing annulment cases. Failure to file within these periods precludes annulment:
- Lack of parental consent: must be filed within five years after reaching 21 years of age.
- Insanity: must be filed anytime before the death of either party.
- Fraud, force, intimidation, or undue influence: within five years after the discovery of fraud or from the cessation of force or intimidation.
- Physical incapacity and sexually transmitted disease: within five years after the marriage.

3. Effects of Annulment

If the annulment is granted, it renders the marriage void from the beginning (void ab initio), subject to the rights of children and third parties who acted in good faith. The court may address matters related to custody, support, and the property relationship between spouses. If annulment is denied due to any defense, the marriage remains valid.

4. Practical Considerations

Burden of Proof: The burden is on the party seeking annulment to prove the grounds by preponderance of evidence.
Best Interest of Children: Courts often weigh the welfare of children in deciding annulment cases, as well as any impact annulment may have on legitimacy, custody, and support.
Good Faith and Equity: Courts apply equitable principles to protect innocent parties, especially in cases involving fraud or misrepresentation.

5. Recent Jurisprudence and Interpretations

Philippine jurisprudence continues to develop around voidable marriages, with courts often emphasizing the sanctity of marriage and interpreting defenses and grounds strictly.