英国准合同制度的演变之路——英美法系返还法的滥觞

The History of Quasi-contract in English Law:The Predecessor of Restitution Law in Common Law

准合同制度是近代英国法中对应于大陆法系不当得利制度的一种返还性救济。本文试图通过英国普通法与衡平法的比较,考察准合同制度在英国法中的历史演变,首先介绍"借债之诉"和"账目之诉"等返还令状,然后梳理"允诺之诉"及其他"准合同性"普通法诉讼格式,如可追索金钱之诉等;进而突出曼斯菲尔德勋爵对英国法中准合同制度的影响,即将衡平法的观念引入准合同制度之中;最后联系普通法与衡平法融合的大背景,研究理论界重提的默示合同理论,分析英国法不当得利概念的成型和准合同制度的没落,从而指出英美法系与大陆法系在不当利益返还这一领域上殊途同归。

Quasi-contract is a restitutionary remedy in the modern history of English law, served as a counterpart of unjust enrichment in civil law countries. This article is to study the evolution of quasicontract in the context of post-medieval English law with the practices of common law and equity law. Firstly two typical medieval writs of recovery--Action of Debt and Action of Account--are introduced; then Assumpsit is speculated. Secondly, attention is paid to the contribution of Lord Mansfield on quasi -contract, i.e. introducing the notion of equity into quasi-contract. Thirdly, given the integration of common law and equity law and the theory of implied contract, the emergence of unjust enrichment and the demise of quasi-contract in English law are explored. Finally, it is concluded that within the domain of restitution law, common law system and civil law system have actually reached the same goal via different routes.