合同自由与等价交换的博弈——英美“约因无须等价”规则研究

The Balance between Contract Freedom and Equal Exchange —On "Consideration Need Not Be Adequate" in Common Law

"约因"是传统英美合同法的核心要件,而"约因必须充足但无须等价"则是法官认定"约因"是否存在进而决定允诺是否有强制力的指导性规则。该规则衍生于英格兰中世纪的合同诉讼,于18世纪后期确立为近现代英美合同法的重要内容。"名义约因"与"虚假约因陈述"是约因无须等价的两种特殊情形。约因无须等价规则的起源与发展生动地诠释了普通法的传统个性,它蕴涵了合同自由的精神,并发挥着促进交易之功能。将合同关系的本质概括为"协作"是当代学者对约因无须等价规则提出的最新哲学辩护。

Consideration is the essential element of traditional common law contracts.The rule of ＂consideration must be sufficient though not necessarily adequate＂is the principal rule of determining whether the sufficient consideration exists.This rule originated in the judicial practice during the medieval times of England,and developed as the essential rule of classical contract laws.Nominal consideration and recital consideration are the special circumstances.The rule has reflected the spirit of contract freedom.It has helped to improve transactions.It also contains the characteristics of common law tradition.Some contemporary scholars have generalized the essence of contractual relationship as＂collaboration＂,which is the recent defense of the rule.