The common law reasonably requires that an offer spell out the essential proposed terms with sufficient definiteness—certainty of terms that enables a court to order enforcement or measure damages in the event of a breach. As it has often been put, “The law does not make contracts for the parties; it merely enforces the duties which they have undertaken” (Simpson, 1965, p. 19). Thus a supposed promise to sell “such coal as the promisor may wish to sell” is not an enforceable term because the seller, the coal company, undertakes no duty to sell anything unless it wishes to do so. Essential terms certainly include price and the work to be done. But not every omission is fatal; for example, as long as a missing term can be fixed by referring to some external standard—such as “no later than the first frost”—the offer is sufficiently definite.
In major business transactions involving extensive negotiations, the parties often sign a preliminary “agreement in principle” before a detailed contract is drafted. These preliminary agreements may be definite enough to create contract liability even though they lack many of the terms found in a typical contract. For example, in a famous 1985 case, a Texas jury concluded that an agreement made “in principle” between the Pennzoil Company and the Getty Oil Company and not entirely finished was binding and that Texaco had unlawfully interfered with their contract. As a result, Texaco was held liable for over $10 billion, which was settled for $3 billion after Texaco went into bankruptcy.
Offers that state alternatives are definitive if each alternative is definite. David offers Sheila the opportunity to buy one of two automobiles at a fixed price, with delivery in two months and the choice of vehicle left to David. Sheila accepts. The contract is valid. If one of the cars is destroyed in the interval before delivery, David is obligated to deliver the other car. Sometimes, however, what appears to be an offer in the alternative may be something else. Charles makes a deal to sell his business to Bernie. As part of the bargain, Charles agrees not to compete with Bernie for the next two years, and if he does, to pay $25,000. Whether this is an alternative contract depends on the circumstances and intentions of the parties. If it is, then Charles is free to compete as long as he pays Bernie $25,000. On the other hand, the intention might have been to prevent Charles from competing in any event; hence a court could order payment of the $25,000 as damages for a breach and still order Charles to refrain from competition until the expiration of the two-year period.