Sigrist v. Century 21 Corp.

519 P.2d 362 (Colo. App. 1973)



Offers to enter into either bilateral or unilateral contracts may not be revoked after acceptance. In the case of an offer for a unilateral contract, an offer which requests return performance rather than a promise to perform, the offer is accepted when substantial performance has been rendered by the offeree. Where one party makes a promissory offer in such form that it can be accepted by the rendition of the performance that is requested in exchange, without any express return promise or notice of acceptance in words, the offeror is bound by a contract just as soon as the offeree has rendered a substantial part of that requested performance.


Defendant race track owner advertised a contest for all race car drivers, with a promised bonus for the point leader at the end of the race season. Plaintiff driver entered his car in the races. He had the most points of any driver when defendant decided to terminate the remaining scheduled races for lack of interest. Plaintiff sued defendant for breach of contract to recover the bonus. The trial court entered judgment for plaintiff. On defendant’s appeal, the appellate court affirmed the trial court’s judgment.


Was defendant race track owner’s promise to pay a bonus for the point leader at the end of the race season a unilateral contract which then became binding upon plaintiff driver’s substantial performance?




Defendant race track owner's promise of a bonus was a unilateral contract, which became binding on defendant once plaintiff driver substantially performed by competing in scheduled races.

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