Case Doctrine:

 ● Marriage is not a mere contract, but a social institution in which the State is vitally interested. The State can find no stronger anchor than on good, solid and happy families. The break-up of families weakens our social and moral fabric; hence, their preservation is not the concern of the family members alone.

 ● In all cases for annulment, declaration of nullity of marriage and legal separation, the prosecuting attorney or fiscal is ordered to appear on behalf of the State for the purpose of preventing any collusion between the parties and to take care that their evidence is not fabricated or suppressed. If the defendant-spouse fails to answer the complaint, the court cannot declare him or her in default but instead, should order the prosecuting attorney to determine if collusion exists between the parties. The prosecuting attorney or fiscal may oppose the application for legal separation or annulment through the presentation of his own evidence, if in his opinion, the proof adduced is dubious and fabricated. 
Facts: Marietta and Rodolfo were married in 1959. They had 8 children. In 1992, Rodolfo left the conjugal home and abandoned Marietta and their children. Two years after, Marietta filed a complaint for the dissolution of the conjugal partnership and judicial separation of property with a plea for support and support pendente lite. At that time, Marietta lived in Las Pinas. The parties entered into a compromise agreement wherein their property located in Carmona, Cavite was adjudicated to Marietta and her children. The court rendered judgment based on the compromise agreement. Conformably thereto, Marietta and her children moved and began residence at the said Carmona property. 

In 1995, Rodolfo, wanting to marry again, filed a case for the declaration of nullity of his marriage with the Marietta on the ground of psychological incapacity. Although the Rodolfo knew that the Marietta was already residing in Carmona, Cavite, he, nevertheless, alleged in his petition that the Marietta was residing at No. 72 CRM Avenue corner CRM Corazon, BF Homes, Almanza, Las Piñas, Metro Manila. The sheriff served the summons and a copy of the petition by substituted service on the the parties’ son, Venancio Mariano B. Ancheta III, at his residence in Bancal, Carmona, Cavite.

Marietta failed to file an answer and was declared in default. Rodolfo was allowed adduce evidence ex-parte. On July 7, 1995, the trial court issued an Order granting the petition and declaring the marriage of the parties void ab initio. The clerk of court issued a Certificate of Finality of the Order of the court on July 16, 1996.

 On July 7, 2000, the Marietta filed a verified petition against the Rodolfo with the Court of Appeals under Rule 47 of the Rules of Court, as amended, for the annulment of the order of the RTC.

 Marietta, alleged, among others, that the order of the trial court nullifying her and the Rodolfo’s marriage was null and void for the court a quo’s failure to order the public prosecutor to conduct an investigation on whether there was collusion between the parties, and to order the Solicitor General to appear for the State.

Held: The records show that for the petitioner’s failure to file an answer to the complaint, the trial court granted the motion of the respondent herein to declare her in default. The public prosecutor condoned the acts of the trial court when he interposed no objection to the motion of the respondent. The trial court forthwith received the evidence of the respondent ex-parte and rendered judgment against the petitioner without a whimper of protest from the public prosecutor. The actuations of the trial court and the public prosecutor are in defiance of Article 48 of the Family Code, which reads:
Article 48. In all cases of annulment or declaration of absolute nullity of marriage, the Court shall order the prosecuting attorney or fiscal assigned to it to appear on behalf of the State to take steps to prevent collusion between the parties and to take care that evidence is not fabricated or suppressed. 
In the cases referred to in the preceding paragraph, no judgment shall be based upon a stipulation of facts or confession of judgment.
The trial court and the public prosecutor also ignored Rule 18, Section 6 of the 1985 Rules of Court (now Rule 9, Section 3[e] of the 1997 Rules of Civil Procedure) which provides:
Sec. 6. No defaults in actions for annulment of marriage or for legal separation.— If the defendant in an action for annulment of marriage or for legal separation fails to answer, the court shall order the prosecuting attorney to investigate whether or not a collusion between the parties exits, and if there is no collusion, to intervene for the State in order to see to it that the evidence submitted is not fabricated.
In the case of Republic v. Court of Appeals, this Court laid down the guidelines in the interpretation and application of Art. 48 of the Family Code, one of which concerns the role of the prosecuting attorney or fiscal and the Solicitor General to appear as counsel for the State:
(8) The trial court must order the prosecuting attorney or fiscal and the Solicitor General to appear as counsel for the state. No decision shall be handed down unless the Solicitor General issues a certification, which will be quoted in the decision, briefly stating therein his reasons for his agreement or opposition, as the case may be, to the petition. The Solicitor General, along with the prosecuting attorney, shall submit to the court such certification within fifteen (15) days from the date the case is deemed submitted for resolution of the court. The Solicitor General shall discharge the equivalent function of the defensor vinculi contemplated under Canon 1095.
The task of protecting marriage as an inviolable social institution requires vigilant and zealous participation and not mere pro-forma compliance. The protection of marriage as a sacred institution requires not just the defense of a true and genuine union but the exposure of an invalid one as well.

A grant of annulment of marriage or legal separation by default is fraught with the danger of collusion. Hence, in all cases for annulment, declaration of nullity of marriage and legal separation, the prosecuting attorney or fiscal is ordered to appear on behalf of the State for the purpose of preventing any collusion between the parties and to take care that their evidence is not fabricated or suppressed. If the defendant-spouse fails to answer the complaint, the court cannot declare him or her in default but instead, should order the prosecuting attorney to determine if collusion exists between the parties. The prosecuting attorney or fiscal may oppose the application for legal separation or annulment through the presentation of his own evidence, if in his opinion, the proof adduced is dubious and fabricated.

Our constitution is committed to the policy of strengthening the family as a basic social institution. Our family law is based on the policy that marriage is not a mere contract, but a social institution in which the State is vitally interested. The State can find no stronger anchor than on good, solid and happy families. The break-up of families weakens our social and moral fabric; hence, their preservation is not the concern of the family members alone. Whether or not a marriage should continue to exist or a family should stay together must not depend on the whims and caprices of only one party, who claims that the other suffers psychological imbalance, incapacitating such party to fulfill his or her marital duties and obligations (Ancheta vs. Ancheta, G.R. No. 145370, March 4, 2004).