Consideration
Contracts & Sales · Lesson 03
Consideration
這一課問的是：兩方之間是否存在「對價」 —— 一場「被磋商出來的、相互的法律不利益交換」？
Actor
Act
Object
Standard
Consequence
Visual Scene · the picture in your head
Issue. Is there consideration — a bargained-for exchange of legal detriments?
這一課問的是：兩方之間是否存在「對價」 —— 一場「被磋商出來的、相互的法律不利益交換」？
Core Terminology · 7 must-know
Tap a card to flip and reveal the meaning.
consideration
Tap to see meaning
A bargained-for exchange of legal detriments between the parties.
對價：當事人間被磋商出來的、相互的法律不利益交換。
legal detriment
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Doing what one is not legally bound to do, or refraining from what one is free to do.
法律不利益：作不必作之事，或放棄可作之事。
bargained for
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Each promise/performance must induce the other.
為交換而磋商：彼此互為誘因。
mutuality of obligation
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Both parties must be bound; otherwise illusory.
義務雙向性：雙方都須受拘束。
pre-existing duty
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Promising to do what one is already obligated to do is not consideration.
既有義務：對既有義務之承諾不構成對價。
past consideration
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Something done before the promise — not bargained-for; not consideration.
過去對價：承諾前已作之事不構成對價。
illusory promise
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A promise that does not actually commit the promisor.
虛幻承諾：實際不拘束承諾人之承諾。
Issue · what this lesson is really about
Is there consideration — a bargained-for exchange of legal detriments?
這一課問的是：兩方之間是否存在「對價」 —— 一場「被磋商出來的、相互的法律不利益交換」？
Trigger words & phrases that should flag this issue:
in exchange forin return forbargained forI promise to X if you do Yagreed to give up
Expression Bank · how lawyers actually say it
Six function → sentence patterns. Use these in essay applications.
| Function | English sentence | 中文 |
|---|---|---|
| Frame question | The question is whether the parties exchanged consideration. | 本題問雙方有無交換對價。 |
| State the test | Each party must suffer a legal detriment bargained for in exchange for the other. | 各方須付出為換取對方之法律不利益。 |
| Negate past | An act performed before the promise is not bargained-for and cannot be consideration. | 承諾前之行為不可為對價。 |
| Negate pre-existing duty | Promising to do what one is already required to do is not consideration. | 履行既有義務不構成對價。 |
| Address adequacy | The law asks whether consideration exists, not whether the bargain was fair. | 法律只問有無對價，不審查公平。 |
| State result | Consideration is therefore satisfied, and the promise is enforceable. | 因此對價成立，承諾可執行。 |
Rule Sentence · the workhorse
Consideration requires a bargained-for exchange in which each party suffers a legal detriment that induces the other party's promise or performance.
Sentence Anatomy · 5 roles, 5 colors
Every rule sentence breaks into five visual roles.
Actor 行為人each contracting party各當事人
Act 行為a promise, performance, or forbearance承諾、履行或不作為
Object 對象the other party's promise or performance對方之承諾或履行
Standard 法律標準bargained-for exchange · mutuality為換取而磋商 / 雙向
Consequence 後果the promise is enforceable承諾可執行
Casebook Snapshot · a real American case
Hamer v. Sidway
Holding. Consideration may consist of forbearance: where one party gives up something he had a legal right to do — drinking, smoking, gambling — at the other's request and in exchange for a promise, that forbearance is a legal detriment supporting the promise. The court does not require the promisor to benefit; the promisee's detriment is enough.
Why it matters. Consideration is about legal detriment that was bargained for — not money or material benefit. Giving up a freedom one was entitled to exercise counts.
對價不限於金錢；放棄合法自由也是對價。
Common Mistakes · what trips students
✗ 「對價」必須是錢。
✓ Consideration can be a promise, performance, or forbearance.
對價可為承諾、行為或不作為。
✗ 法院會看交易是否「公平」。
✓ Adequacy is not the question — existence is.
法律不審查 adequacy。
✗ 已經做完的事可以作為對價。
✓ Past consideration is not consideration.
過去對價不構成對價。
✗ 贈與（gift）也是合約。
✓ Gift promises lack consideration; consider promissory estoppel.
贈與承諾無對價；可訴諸 promissory estoppel。
Mini IRAC · build the Application
Issue. Did the parties exchange consideration when D promised to pay P $5,000 if P refrained from smoking until P's 21st birthday?
Rule. Consideration requires a bargained-for exchange in which each party suffers a legal detriment that induces the other's promise.
Application (model). D promised P $5,000 in exchange for P giving up smoking — a freedom P had every legal right to exercise — until P turned 21. Because consideration is a bargained-for exchange of legal detriments, the fact that P's forbearance from a legal activity was the very thing D asked for in return for the promise means the two commitments induced each other.
Pick the right element for each blank:
g1.
g2.
g3.
Conclusion. Therefore, consideration is satisfied, and D's promise is enforceable.
MBE Check · multiple choice
After P rescued D's child from a fire on her own initiative, D promised P $10,000 "in recognition of what you did." Is D's promise supported by consideration?
Mini Essay · write the Application paragraph
Facts. D, a builder, contracted to build P's house for $300,000. Halfway through the job, D demanded an additional $20,000 to finish at the original quality. P, anxious to move in, agreed in writing. After completion, P refused to pay the extra $20,000.
Call. Is D entitled to the extra $20,000?
Practice Drill · tap to build the rule
Drop the chips here in correct order:
Tap chips to add → tap chips in the target to remove: