G.R. No. L-69996 December 5, 1994
DR. FERNANDO PERIQUET, JR., petitioner, vs. HONORABLE FOURTH CIVIL CASES DIVISION OF THE INTERMEDIATE APPELLATE COURT and the HEIRS OF THE LATE FELIX R. FRANCISCO, respondents.

FACTS

Spouses Fernando Periquet and Petra Francisco died childless. Petra died intestate, survived by her siblings and their children. Prior to her death, Petra had an unsigned will prepared that would have instituted petitioner Fernando Periquet, Jr., a son of Petra’s sister whom the spouses reared, as her universal heir, with specific legacies totaling P50,000.00 to other relatives, including P10,000.00 to her brother Felix Francisco. After Petra’s death, Felix Francisco executed a Deed of Assignment, transferring all his hereditary rights in Petra’s intestate estate to Periquet, Jr., expressly motivated by his desire to honor the wishes in the unsigned will. Other heirs executed similar assignments.
Subsequently, a compromise agreement was approved by the probate court, partitioning Petra’s estate among Periquet, Jr. and the other assignees, excluding Felix Francisco as he had already assigned his rights. After Felix Francisco’s death, his heirs filed an action to annul his assignment, alleging it was procured through fraud and undue influence. The trial court upheld the assignment’s validity. The Intermediate Appellate Court reversed, declaring the assignment void, reasoning that Felix Francisco was mistaken in believing he was obligated to honor the unsigned will, which had no legal effect.

ISSUE

Whether the Deed of Assignment of Hereditary Rights executed by Felix Francisco in favor of Fernando Periquet, Jr. is valid.

RULING

Yes, the assignment is valid. The Supreme Court reversed the Appellate Court. The legal logic centers on the nature of consent and mistake in contracts. For mistake to vitiate consent under Article 1330 of the Civil Code, it must refer to the substance of the thing which is the object of the contract, or to those conditions which have principally moved one or both parties to enter into the contract. Here, Felix Francisco’s alleged mistake pertained to a supposed moral obligation to comply with an unsigned will, which is a motive for entering into the contract, not an error as to the nature or object of the contract itself. The object of the contract was the assignment of his hereditary rights, and he was not mistaken about what those rights were or that he was transferring them. Mistake of motive, especially when the true motive (to honor Petra’s wishes) is stated in the deed, does not invalidate consent. Furthermore, the assignment was a perfected contract from its execution in 1966. The heirs of Felix Francisco, who were not parties to the compromise agreement approved by the court, have no standing to seek its modification or to challenge the assignment collaterally long after its execution and the estate proceedings had been closed. The assignment was a valid act of disposition of an expectant right.