第五单元：合同法（二）
Master consideration, intention to create legal relations, and apply IPAC to contract problems.
掌握对价、创设法律关系的意图，并将IPAC方法应用于合同法问题。
合同的基本要素
A valid contract requires three essential elements:
一个有效的合同需要三个基本要素：This unit focuses on the remaining two essential elements: Consideration and Intention to create legal relations.
本单元重点讨论其余两个基本要素：对价和创设法律关系的意图。💡 Remember 记住: Without ALL three elements (agreement, consideration, intention), there is NO enforceable contract.
记住：缺少三个要素中的任何一个（合意、对价、意图），就不存在可执行的合同。对价（约因）
Definition: Something of legal value exchanged for a promise. The "price" paid or given in return for a promise.
定义：为换取承诺而交换的具有法律价值的东西。为承诺而支付的"代价"。Essential in every simple contract. No consideration = no contract = promise unenforceable.
每个简单合同都必须有对价。没有对价 = 没有合同 = 承诺不可执行。对价的类型
A promise to do something in the future. E.g. X promises to pay Y in return for Y's promise to wash X's car.
对未来做某事的承诺。例如：X承诺付钱给Y，以换取Y承诺洗X的车。✅ VALID 有效
Performing a required act. E.g. Carlill v Carbolic Smoke Ball Co — using the product as directed constituted executed consideration.
执行所要求的行为。例如：Carlill v Carbolic Smoke Ball Co — 按指示使用产品构成已执行对价。✅ VALID 有效
Consideration that pre-dates the promise. E.g. X promises to pay Y after Y has already completed the work without any prior agreement.
先于承诺的对价。例如：在没有事先约定的情况下，Y已完成工作后X才承诺付款。❌ NOT VALID 无效
关键规则
对价关键判例
Facts: Roscorla purchased a horse from Thomas for £30. After the purchase was completed, Thomas promised the horse was "free from vice" (sound and well-behaved).
事实：Roscorla以30英镑从Thomas处购买了一匹马。购买完成后，Thomas承诺这匹马"没有恶习"（健康且性情良好）。Issue: Was Thomas's promise supported by consideration?
问题：Thomas的承诺是否有对价支持？Held: The promise was NOT supported by consideration. The payment of £30 was PAST consideration — it had already been given before the promise was made. Therefore the promise was not enforceable.
判决：该承诺没有对价支持。30英镑的付款是过去的对价——在承诺作出之前就已经支付了。因此该承诺不可执行。⚖️ Principle 原则: Past consideration is not good consideration.
过去的对价不是有效的对价。Facts: Sailors contracted to sail a ship for a round-trip voyage. During the voyage, two sailors deserted. The captain promised the remaining sailors extra wages if they sailed the ship short-handed back to London.
事实：水手们签约驾船进行往返航行。航行期间，两名水手逃跑了。船长承诺如果剩余水手在人手不足的情况下把船开回伦敦，将支付额外工资。Issue: Were the remaining sailors entitled to the extra wages?
问题：剩余水手是否有权获得额外工资？Held: The promise was NOT supported by fresh consideration. The sailors were already under an existing contractual duty to sail the ship. Performing an EXISTING duty is NOT sufficient consideration for a new promise.
判决：该承诺没有新的对价支持。水手们已经有驾船的合同义务。履行现有义务不构成新承诺的充分对价。⚖️ Principle 原则: Performance of an existing contractual duty is not good consideration.
履行现有合同义务不是有效的对价。创设法律关系的意图
Parties must intend their agreement to have legal consequences.
各方必须有意使其协议具有法律后果。The court determines intention objectively — what would a reasonable person conclude?
法院客观地确定意图——一个理性人会得出什么结论？两种推定
| Type 类型 | Presumption 推定 | Rebuttable? 可推翻？ | Examples 例子 |
|---|---|---|---|
| Social / Domestic Agreements 社交/家庭协议 |
NO intention ❌ 推定没有创设法律关系的意图 |
YES ✅ 可被推翻（可用证据推翻） |
Agreements between family members, friends, social arrangements 家庭成员之间、朋友之间、社交安排的协议 |
| Commercial / Business Agreements 商业/商务协议 |
YES, intention ✅ 推定有创设法律关系的意图 |
YES ✅ 该推定也可被推翻 |
Business contracts, employment agreements, sales transactions 商业合同、雇佣协议、销售交易 |
创设法律关系意图的关键判例
Facts: Husband worked in Ceylon (Sri Lanka). He promised his wife £30 per month while she stayed in England for health reasons. The marriage later broke down.
事实：丈夫在锡兰（斯里兰卡）工作。他承诺妻子因健康原因留在英国期间每月支付30英镑。婚姻后来破裂。Issue: Was there a binding contract between husband and wife?
问题：丈夫和妻子之间是否存在具有约束力的合同？Held: No binding contract. This was a DOMESTIC agreement — the presumption is NO intention to create legal relations. The presumption was NOT rebutted.
判决：不存在具有约束力的合同。这是家庭协议——推定没有创设法律关系的意图。该推定未被推翻。Facts: Husband and wife had SEPARATED. The husband agreed IN WRITING to transfer the house to the wife if she paid the remaining mortgage instalments.
事实：丈夫和妻子已经分居。丈夫书面同意，如果妻子偿还剩余的抵押贷款分期付款，就将房屋转让给她。Issue: Was there intention to create legal relations despite being a family matter?
问题：尽管是家庭事务，是否有创设法律关系的意图？Held: Yes — the presumption was REBUTTED. The couple had separated, and the agreement was in writing. These factors showed clear intention to be legally bound.
判决：是的——推定被推翻了。夫妻已经分居，协议是书面的。这些因素表明有明确的法律约束意图。Facts: A couple relocated from England to Australia based on the brother-in-law's promise to provide accommodation and leave them his estate in his will.
事实：一对夫妻基于姐/妹夫承诺提供住所并在遗嘱中留给他们遗产，从英国搬到了澳大利亚。Issue: Was there intention to create legal relations in this family arrangement?
问题：这个家庭安排中是否有创设法律关系的意图？Held: Yes — the presumption of no intention was REBUTTED. The couple gave up their life in England and relocated to Australia — this showed the parties intended legal consequences.
判决：是的——没有意图的推定被推翻了。夫妻放弃了在英国的生活搬到澳大利亚——这表明各方意图产生法律后果。Facts: A church leader (Archbishop) argued his engagement with the Church was a binding employment contract.
事实：一位教会领袖（大主教）主张他与教会的聘用关系是具有约束力的雇佣合同。Issue: Does the presumption against intention apply in a religious/voluntary context?
问题：在宗教/志愿者背景下，反对意图的推定是否适用？Held: The High Court said the presumption against intention in a religious context is REBUTTABLE. The court must consider ALL the circumstances of the case, not merely apply a blanket presumption.
判决：高等法院认为在宗教背景下反对意图的推定是可以被推翻的。法院必须考虑案件的所有情况，而不是仅仅适用一个笼统的推定。合同法问题的IPAC分析方法
Apply the IPAC method specifically to contract law problems involving consideration and intention.
将IPAC方法专门应用于涉及对价和意图的合同法问题。识别合同法问题
Identify the contract law issue. Is it about offer, acceptance, consideration, or intention?
识别合同法问题。是关于要约、承诺、对价还是意图？陈述相关合同法原则
State the relevant contract law principles. Define consideration/intention rules. Cite relevant cases (e.g. Roscorla v Thomas, Balfour v Balfour).
陈述相关的合同法原则。定义对价/意图规则。引用相关判例。将原则应用于事实
Apply principles to the facts. Was there valid consideration? Was it past, executed, or executory? Is this a domestic or commercial agreement? Has the presumption been rebutted?
将原则应用于事实。是否有有效的对价？是过去的、已执行的还是待执行的？这是家庭协议还是商业协议？推定是否被推翻？提供基于分析的结论
State whether a valid contract exists based on your analysis.
根据你的分析说明是否存在有效的合同。Tom agrees to sell his car to Jerry for $5,000. After Jerry pays, Tom discovers the car has a hidden defect and promises Jerry the car is "mechanically perfect." Is Tom's promise enforceable? Apply IPAC.
Tom同意以5,000澳元将他的车卖给Jerry。Jerry付款后，Tom发现车有一个隐藏缺陷，并向Jerry承诺车"机械状况完好"。Tom的承诺是否可以执行？应用IPAC分析。💡 Hint 提示: Consider whether Jerry's payment of $5,000 is past consideration in relation to Tom's later promise. Think about Roscorla v Thomas.
考虑Jerry支付的5,000澳元相对于Tom后来的承诺是否构成过去的对价。想想 Roscorla v Thomas 案。闪卡复习
Click each card to reveal the definition. Master these key terms!
点击每张卡片查看定义。掌握这些关键术语！知识检测
Test your understanding of Contracts Part 2. Select the correct answer for each question.
测试你对合同法（二）的理解。为每个问题选择正确答案。