In Philippine succession law, a common point of conflict arises when heirs attempt to claim ownership over property that their predecessor (the deceased) sold during their lifetime. To navigate this, one must distinguish between the rights of ownership, the finality of contracts, and the specific protections afforded to "compulsory heirs" under the Civil Code.

The Principle of Transmission

Under Article 777 of the Civil Code, the rights to the succession are transmitted from the moment of the death of the decedent. This means heirs only inherit what remains in the estate at the time of death.

If a property was validly sold by the owner while they were still alive, that property ceased to be part of their assets. Consequently, it does not form part of the inheritance (the "hereditary estate"). Heirs cannot generally claim a property that their predecessor no longer owned at the time of passing.

The Validity of the Sale

The primary hurdle for any heir seeking to "recover" sold property is the validity of the contract of sale. For a sale to be binding and effectively remove the property from the future estate, it must meet the three essential elements of a contract:

Consent: The seller must have had the capacity and free will to sell.
Object Certain: The specific property being sold.
Cause or Consideration: The price paid for the property.

If these elements are present, the sale is valid, and the heirs are bound by it. Under the principle of privity of contracts, the heirs are considered the "privies" or successors-in-interest of the seller. They "step into the shoes" of the decedent and must respect the contracts the decedent entered into.

Grounds for Challenging a Sale

Heirs may only successfully claim or "void" a sale if they can prove the transfer was not legally valid. Common legal grounds include:

Simulated Sales: If the sale was "fake" (e.g., a father "sells" to one child for $0 to avoid taxes or bypass other siblings), it may be considered a relatively or absolutely simulated contract. If no money actually changed hands, the court may treat the "sale" as a donation or declare it void.
Lack of Capacity: If the decedent was of unsound mind, senile, or under duress/undue influence at the time of the sale, the contract is voidable.
Vitiated Consent: If the sale was obtained through fraud or mistake.
Sale of Conjugal Property: Under the Family Code, if the property is conjugal (owned by both spouses) and one spouse sells it without the written consent of the other, the sale is generally considered void, not merely voidable. In this case, the heirs of the non-consenting spouse may have a strong claim to nullify the sale.

The Issue of "Legitime" and Inofficious Donations

A frequent misconception is that a parent cannot sell property because it "belongs" to the children's future inheritance. However, Philippine law allows an owner the absolute right to dispose of their property during their lifetime (jus disponendi), provided the sale is for a valuable consideration.

The concept of Legitime—the part of the estate reserved by law for compulsory heirs—only applies to the property remaining after death and to donations.

If a sale is genuine and for a fair price, the "legitime" is not violated because the property is simply replaced by cash (the purchase price) in the decedent's assets.
If a sale is actually a "disguised donation" (e.g., sold for a price far below market value), the heirs may later claim it was inofficious. This means the transfer impaired their legitime, and they may seek to reduce or revoke the transfer upon the death of the decedent.

Summary of Legal Standing

During the Seller's Lifetime: Heirs have no "vested right" to the property. They have a mere "expectancy." They cannot sue to stop a sale unless they can prove the seller is legally incompetent and they are appointed as legal guardians.
After the Seller's Death: Heirs can file an action for "Annulment of Sale" or "Reconveyance" if they can prove the sale was fraudulent, simulated, or lacked the essential requirements of a contract.

Conclusion

In the Philippine context, a valid sale is near-absolute. Heirs cannot reclaim property simply because they believe they should have inherited it. To succeed, the burden of proof lies heavily on the heirs to demonstrate that the sale was a legal fiction or suffered from a fatal defect that rendered it void from the beginning. Without such proof, the law protects the buyer and the finality of the transaction.