⚡ 10-Second Rule
Courts enforce promises that were traded for something, not promises handed out like gifts.
🧒 ELI-10 Scene
Ava tells her brother Theo, "You're the best — I'm giving you my skateboard Saturday." Saturday comes, and Ava keeps the board. Annoying, but nobody can make her hand it over. She promised a gift, and Theo gave nothing back. Now change one thing: "I'll give you my skateboard if you do my dishes this week." Theo scrubs every plate. Now Ava is stuck — they made a trade. It doesn't matter that dishes are worth way less than a skateboard. A trade is a trade, even a lopsided one. But Theo can't point at the lawn he mowed last month and call that his side. Yesterday's favor can't be today's trade.
⚖️ Actual Rule
Consideration requires a bargained-for exchange: each side's promise or performance must be the price the other side asked for and paid — the promise was made to get that return, and the return was given to get the promise (Restatement (Second) of Contracts § 71, paraphrasing). Courts require sufficiency, not adequacy — there is no requirement that the values exchanged be equivalent, so even a nominal-seeming exchange suffices if genuinely bargained for (Restatement § 79, paraphrasing). Past consideration is no consideration: an act already completed cannot be exchanged for a later promise. Under the preexisting duty rule, doing or promising what one is already legally obligated to do is not consideration (Restatement § 73, paraphrasing); in Alaska Packers' Ass'n v. Domenico, 117 F. 99 (9th Cir. 1902), the court refused to enforce a mid-voyage promise of higher wages to seamen who merely did the work their existing contracts already required. A modification can still bind at common law if supported by new consideration or, under Restatement § 89 (paraphrasing), if fair and equitable in light of circumstances not anticipated when the contract was made. For sales of goods, UCC § 2-209(1) abolishes the requirement: "An agreement modifying a contract within this Article needs no consideration to be binding" — though the modification must be sought in good faith.
ELI-10 translation: a promise binds when each side gave something to get something, the court won't weigh fairness, old favors don't count, and already-owed work doesn't count — unless the deal is for goods, where honest changes stick without a new trade.
🔍 Ask These Questions
- Did the promisor ask for something in exchange for the promise? (Was the promise fishing for a return, or just being nice?)
- Did the promisee actually give that something — an act, a promise, or giving up a legal right? (Did the other side pay their half of the trade?)
- Is someone attacking the deal as unfair or lopsided? (Courts check that a trade exists, not that it's a good one.)
- Is the claimed consideration something already done before the promise? (Yesterday's favor can't buy today's promise.)
- Is the claimed consideration something the person already legally owed? (Doing your existing job isn't giving anything new.)
- Is this a modification of a contract for goods? (For goods, an honest change needs no new trade at all.)
- If the preexisting duty rule blocks a modification, were there truly unanticipated circumstances making the change fair? (A surprise nobody saw coming can rescue an honest adjustment.)
⚠️ Bar Trap
Exam language: Examiners stage a mid-performance demand for more money and have the other party promise to pay it. Under the common-law preexisting duty rule, that promise fails for want of consideration — but the same facts involving a sale of goods succeed under UCC § 2-209(1), which requires only good faith, not consideration. The trap is applying the wrong body of law to the transaction.
ELI-10: First ask what's being sold. If it's work or land, a "pay me more for the same job" promise is empty. If it's goods, an honest change sticks with no new trade. Mixing up the two lanes is the classic wrong turn.
🧪 Question
A homeowner hired a contractor to build a backyard deck for $8,000, payable on completion. Halfway through the project, with materials already purchased and no unexpected site conditions, the contractor told the homeowner, "I've been losing money on jobs lately. I won't finish unless you agree to pay $10,000." Worried about delay, the homeowner said, "Fine, $10,000 — just finish it." The contractor completed the deck exactly as the original contract specified. The homeowner paid $8,000 and refused to pay more. The contractor sued for the additional $2,000.
Is the contractor likely to recover the additional $2,000?
(A) Yes, because the homeowner voluntarily agreed to the higher price. (B) Yes, because the UCC permits good-faith modifications without new consideration. (C) No, because the contractor gave no new consideration for the promise of the additional $2,000. (D) No, because a contract modification is unenforceable unless it is in writing.
Answer: (C). This is a services contract governed by common law. The contractor merely completed work already owed under the original contract, so the preexisting duty rule leaves the $10,000 promise unsupported by consideration, and no unanticipated circumstances justify the change.
💡 Why the Wrong Answers Are Wrong
- (A) treats voluntariness as a substitute for consideration; even a willing promise fails without a bargained-for exchange.
- (B) applies UCC § 2-209(1) to a services contract; building a deck is not a sale of goods.
- (D) invents a writing requirement; the modification fails for lack of consideration, not lack of a writing.
- ELI-10: The misconception is thinking "she agreed, so she owes it." Agreement alone isn't enough — the contractor had to bring something new to the table, and he brought only the work he already owed.
