"x x x.
Estoppel is an equitable principle rooted in natural justice; it is meant to prevent persons from going back on their own acts and representations, to the prejudice of others who have relied on them.[47] Article 1431 of the Civil Code provides:
Through estoppel an admission or representation is rendered conclusive upon the person making it, and cannot be denied or disproved as against the person relying thereon.
Article 1431 is reflected in Rule 131, Section 2 (a) of the Rules of Court, viz.:
Sec. 2. Conclusive presumptions. — The following are instances of conclusive presumptions:
(a) Whenever a party has by his own declaration, act or omission, intentionally and deliberately led another to believe a particular thing true, and to act upon such belief, he cannot, in any litigation arising out of such declaration, act or omission be permitted to falsify it.
This Court has identified the elements of estoppel as:
[F]irst, the actor who usually must have knowledge, notice or suspicion of the true facts, communicates something to another in a misleading way, either by words, conduct or silence; second, the other in fact relies, and relies reasonably or justifiably, upon that communication; third, the other would be harmed materially if the actor is later permitted to assert any claim inconsistent with his earlier conduct; and fourth, the actor knows, expects or foresees that the other would act upon the information given or that a reasonable person in the actor's position would expect or foresee such action.[48]
This liability of PRHC, however, has a ceiling. The escalation agreement entered into was for P 36 million—the maximum amount that LCDC contracted itself to infuse and that PRHC agreed to reimburse. Thus, the Court of Appeals was correct in ruling that the P 2,248,463.92 infused by LCDC over and above the P 36 million should be for its account, since PRHC never agreed to pay anything beyond the latter amount. While PRHC benefited from this excess infusion, this did not result in its unjust enrichment, as defined by law.
Unjust enrichment exists “when a person unjustly retains a benefit to the loss of another, or when a person retains money or property of another against the fundamental principles of justice, equity and good conscience.”[49] Under Art. 22 of the Civil Code, there is unjust enrichment when (1) a person is unjustly benefited, and (2) such benefit is derived at the expense of or with damages to another.[50] The term is further defined thus:
Unjust enrichment is a term used to depict result or effect of failure to make remuneration of or for property or benefits received under circumstances that give rise to legal or equitable obligation to account for them; to be entitled to remuneration, one must confer benefit by mistake, fraud, coercion, or request.[51]
In order for an unjust enrichment claim to prosper, one must not only prove that the other party benefited from one’s efforts or the obligations of others; it must also be shown that the other party was unjustly enriched in the sense that the term “unjustly” could mean “illegally” or “unlawfully.”[52] LCDC was aware that the escalation agreement was limited tox x x."
