Whether Rupert Whitehead's April 12 letter offered a unilateral contract that could be accepted only by performance, or a bilateral contract that could be accepted by a return promise.
Holding
It offered a bilateral contract. The Davises accepted it by their April 14 letter promising to come to California and perform the requested services.
Reasoning
A unilateral contract is formed when the offeror seeks actual performance rather than a return promise; a bilateral contract is formed through reciprocal promises. Although an offeror may specify either form, when the offer is reasonably uncertain, contract law presumes that the offer invites a bilateral contract. That construction is favored because mutual promises immediately bind and protect both parties.
The surrounding circumstances showed that Rupert wanted assurance, not completed performance as the sole means of acceptance. He was desperate for trusted assistance, had confidence in the Davises, and asked them to let him hear from them “as soon as possible.” That request for an immediate response indicated that he sought their commitment to come and help him.
The promised services also extended beyond Rupert's own life, particularly the obligation to care for Blanche until her death. Because Rupert could die before all performance was complete, he necessarily had to rely on the Davises' promise to carry out those obligations. This structure strongly supported construing the proposal as bilateral.
Frank Davis immediately sent an unequivocal acceptance stating that he and Caro accepted Rupert's proposition and would travel to California. Rupert received that letter and did not reject its method of acceptance. The return promise therefore created a binding contract before Rupert's death.