Short answer. The law in force when he signed it. A will's formal validity is judged by the law in effect at the time it was made, not the law at death. A later change in the formal requirements neither validates a will that was defective when signed nor invalidates one that was properly executed.
What the law says
The validity of a will as to its form depends upon the observance of the law in force at the time it is made.
Civil Code, Article 795 — Formal Validity Is Fixed at Execution. Read the full provision →
Form is frozen at execution
Article 795 fixes the point in time for testing a will's form: the validity of a will as to its form depends upon the observance of the law in force at the time it is made. So the question is not what the formal rules were when your father died, or when the will is offered for probate, but what they were on the day he signed. A will executed in proper form under the law then in force stays formally valid even if the requirements later change, and a change in the law after signing does not reach back to affect it.
The rule cuts both ways
Freezing form at execution has two consequences that mirror each other. A will that met every formal requirement when made cannot be undone by a later statute that adds or alters formalities; it was valid when it was born and remains so. Equally, a will that failed the formalities in force when it was signed is not rescued by a subsequent law that would have accepted it, because it was void from the start and there was nothing to validate. The testator and his witnesses are entitled to rely on the rules that existed at the moment they acted.
Form is not the same as substance
This article governs form, the execution requirements: the writing, the signing, the number and manner of witnesses, the attestation. It does not settle every question a will can raise. How much a testator may give away, who his compulsory heirs are and what shares the law reserves for them, the intrinsic content of the dispositions, are governed by different rules and a different reference point. So establishing that the will was properly executed under the old formalities answers the formal question only; the substantive limits on what the will can do are judged separately.
What to establish in your case
The practical enquiry is narrow and factual. Pin down the date the will was executed, then measure the document against the formal requirements that were in force on that date, not today's. If it complied then, the intervening change is irrelevant to its form and the will can be admitted to probate on that footing. If it did not comply then, the later, more lenient law does not save it. A lawyer comparing the will against the formalities applicable at signing can tell you quickly which side of the line it falls on.
Cases citing this provision
These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.
- Testate Estate of the Late Alipio Abada, et al. vs. Alipio Abaja, et al, G.R. No. 147145, January 31, 2005 — read the decision on LawPhil →