Rodolfo G. Cruz v. Atty. Delfin Gruspe

Summary

This Supreme Court case arose from a vehicular collision where the bus owner and a barangay official signed a Joint Affidavit of Undertaking promising to replace the damaged car or pay P350,000.00 with 12% monthly interest. When they failed to comply, the car owner sued for collection. The key legal issue was whether the Joint Affidavit constituted a valid contract. The Supreme Court affirmed that despite its title, the document was indeed a contract containing all essential elements under Civil Code Article 1318. The Court rejected claims of vitiated consent due to lack of evidence and affirmed the contract's validity. However, it modified the judgment by ruling that interest should accrue only from the filing of the judicial demand (complaint) rather than from the original deadline, and implicitly approved the reduction of the excessive 12% monthly interest rate to 12% per annum. The case establishes important precedents on contract interpretation, the irrelevance of document titles in determining legal nature, and requirements for proving vitiated consent.