G.R. No. 1492 : April 15, 1904
TAN MACHAN, plaintiff-appellee, vs. MARIA GAN AYA DE LA TRINIDAD, ET AL., defendants-appellants.

FACTS:
Plaintiff Tan Machan filed an action against the heirs and legal representatives of the deceased Ruperta Gualinco, and against Carmen Cañete who had a contract to purchase Gualinco’s hacienda. Tan Machan alleged that on August 9, 1894, Gualinco executed a promissory note for $9,000 in favor of Clemente Zulueta, and that he (Tan Machan) and Lim Ponson signed the note as sureties. Upon Gualinco’s failure to pay, Tan Machan paid the debt and sought to be subrogated to Zulueta’s rights. He prayed for judgment for the amount due and that Gualinco’s mortgaged property be subjected to his claim. The defendants-heirs denied Tan Machan was a surety, alleging he and Lim Ponson were joint principals with Gualinco and that the loan proceeds were equally divided among them. The trial court ruled in favor of Tan Machan, holding him to be a surety and ordering payment from the estate’s property.

ISSUE:
1. Whether the trial court erred in admitting parol evidence to prove that Tan Machan and Lim Ponson signed the promissory note as sureties, contrary to the rule that oral evidence cannot contradict a written instrument.
2. Whether the trial court erred in admitting Tan Machan’s books of account as evidence.

RULING:
The Supreme Court affirmed the trial court’s judgment.
1. On the parol evidence: The trial court did not err in admitting testimony to show Tan Machan and Lim Ponson signed as sureties. The rule prohibiting oral evidence to contradict a written instrument was not violated because the nature of the relationship between the co-signers (whether as principals or sureties) is a collateral agreement not purportedly covered by the terms of the promissory note itself. Such an agreement may be proven by extrinsic evidence.
2. On the books of account: The objection at trial was solely that the books were not kept in accordance with the Code of Commerce. The bill of exceptions, however, contained no statement of facts showing how the books were deficient. An appellate court cannot consider grounds for objection not raised at trial. Furthermore, books of account are admissible under Sections 328 and 338 of the Code of Civil Procedure (as memoranda or records of a deceased person or to refresh memory) independently of the Code of Commerce, provided their foundational requirements are met. The additional objection based on Article 1228 of the Civil Code, raised only on appeal, was not considered.
The Court also declined to review the factual finding that Tan Machan was a surety, as no motion for a new trial was filed, precluding a re-examination of the evidence under Section 497 of the Code of Civil Procedure. Costs were adjudged against the defendants-appellants.