Cal. Evid. Code § 623 : CALIFORNIA EVIDENCE CODE — BURDEN OF PROOF; BURDEN OF PRODUCING EVIDENCE; PRESUMPTIONS AND INFERENCES — PRESUMPTIONS AND INFERENCES — CONCLUSIVE PRESUMPTIONS — Contradiction of deliberate statement or conduct

Whenever a party has, by his own statement or conduct, intentionally and deliberately led another to believe a particular thing true and to act upon such belief, he is not, in any litigation arising out of such statement or conduct, permitted to contradict it.