1 Cal. 2d 370, 34 P.2d 1026 (Cal. 1934)
Davis v. Jacoby is a foundational California Supreme Court case on offer-and-acceptance, particularly the line between unilateral and bilateral contracts.
When an offer requests that relatives come render care and states that the offerors will leave them their property if they do so, and asks for an immediate response, does the offeree's mailed promise to come create a binding bilateral contract before the offeror's death, or is the offer only acceptably by completed performance (a unilateral contract) such that the death revokes the offer?
If an offer is reasonably susceptible of acceptance either by a promise or by performance, courts presume it invites a promise and forms a bilateral contract upon the offeree's return promise. Acceptance by mail is effective upon dispatch under the mailbox rule, unless the offer prescribes a different method. Death of the offeror revokes an unaccepted offer, but it does not terminate a contract already formed by acceptance. A clear and definite contract to make a will is specifically enforceable in equity, and courts may impress a constructive trust on the estate to effectuate the bargain.
The court held that the Jacobys' letters invited acceptance by promise, not only by performance; the Davises accepted by mailing their promise to come. A binding bilateral contract was formed upon dispatch of the acceptance before Mr. Jacoby's death. The contract to leave property was enforceable in equity against the estate.
For law students, Davis v. Jacoby anchors several first-year Contracts doctrines. It establishes a strong presumption that ambiguous offers invite a return promise (bilateral contracts), mitigating forfeiture risks and protecting reliance. It cleanly demonstrates the mailbox rule's operation even when the offeror dies before receiving acceptance. And it exemplifies the enforceability of contracts to make a will, highlighting equitable remedies like constructive trusts. On exams, Davis guides interpretation of offers that both request action and ask for an immediate commitment, and it counsels careful analysis of whether acceptance occurred—and by what mode—before an intervening event (like death) could terminate the offer.