Elsinore Union Elementary School District v. Kastorff
Supreme Court of California
353 P.2d 713 (1960)
The day after submitting his bid, contractor Kastorff (defendant) discovered he had omitted plumbing costs, lowering his bid by $6,500, and promptly notified Elsinore (plaintiff) through his architect and then a personal letter asking to withdraw; Elsinore nonetheless refused to release him and sent written acceptance, then after Kastorff didn't sign, accepted a more expensive replacement bid and sued him for the price difference, and the trial court found Elsinore wasn't on notice of any mistake.
Whether an offeror can rescind a contract if the offer was based on a material mistake of fact and the offeree knew, or had reason to know at the time of accepting that the offer was based on a mistake.