相互性原则(Mutuality Principle)是苏格兰合同法中的一项原则。它的最初意义是强调:在一个双务合同当中,如果一方当事人不履行自身的义务,他不得要求对方履行合同义务。然而,随着苏格兰合同法判例的不断发展,此项原则逐步被赋予了一项新的含义,即,违约方不得提起诉讼,要求对方针对违约方已履行的给付进行返还(英文为recovery,在本文中译为“返还”)。现今,苏格兰的学术界和法官们越来越意识到这项新含义的不合理性。本文将针对此项原则的原始意义、理论发展、对违约方的不公平性以及解决方法展开论述。本文的第一部分叙述了针对相互性原则的两种不同的观点,即案例中有关剥夺违约方请求返还权利的判词和学术界对这种观点的质疑,并主张完全使违约方丧失救济权利的做法并非公平。第二部分是有关苏格兰法院是如何保护违约方利益的内容。在司法实践中,苏格兰的法官们在承认相互性原则新含义的效力的同时,规避了对它的运用。他们提出,虽然违约方不能以合同为由提起要求守约方返还的诉讼,但违约方却可以以不当得利(Unjustified Enrichment)的方法请求司法支持。在第三部分中,本文介绍并对比了其他普通法法域(common law jurisdictions),特别是在英格兰法中,以及中国法中的相关制度。本文的第四部分就违约方可采取请求返还的方法展开论述,并提出违约方首先应当有权以合同为由要求守约方针对其已给付之履行进行返还,但此种方法有时并不能对合同双方进行公平的保护,所以违约方在某些情况下应当有权以不当得利的方法提起诉讼。而当两种方法被归结为一起,即可以适用《欧洲合同法原则》第9:903条所规定的比较灵活的方法。第五部分的主要内容为对违约方返还请求权的限制,即在四种情况下违约方虽然进行了部分履行或瑕疵履行,其也不能要求守约方予以返还。在本文最后的结论部分中,笔者认为作为公平原则的体现,违约方在其履行价值大于对方因违约所受损失时,应当享有返还请求权,并应当采用《欧洲合同法原则》第9:903条所规定的方法以公平地保护违约方的利益。 Mutuality Principle is a principle in Scottish contract law. Its initial significance was to underline that in a double-service contract, a party may not require the other party to perform its contractual obligations if it fails to fulfill its obligations. However, with the continuous development of the jurisprudence of the contract law in Scotland, this principle is gradually being given a new meaning that the defaulting party can not bring a lawsuit and require the other party to return the defaulted party's paid performance (in English, This article translated as “return ”). Nowadays, academics and judges in Scotland are increasingly aware of the irrationality of this new meaning. This article will address the original meaning of the principle, theoretical development, the injustice of the non-compliance side and solution to start the discussion. The first part of the article describes two different viewpoints on the principle of reciprocity, namely, the judgment in the case concerning the denial of the right to return by the defaulting party and the question in the academic community about this view and the claim that the party who completely defraud should lose the right to remedy Not fair. The second part is about how the Scottish court protects the interests of the defaulting party. In judicial practice, judges in Scotland, while acknowledging the validity of the new meaning of the principle of reciprocity, circumvent the application of it. They argue that while the defaulting party can not file a lawsuit for the defaulting party to return on the grounds of the contract, the defaulting party may request judicial support in the form of Unjustified Enrichment. In the third part, this article introduces and contrasts with other common law jurisdictions, especially in England law and the Chinese system. The fourth part of this article discusses the method that the defaulting party can take the request for return, and proposes that the defaulting party should first of all have the right to require the defensive principle to return the performance of the paid performance on the ground of the contract, but sometimes this method can not The two parties to the contract have fair protection, so the defaulting party should in some cases have the right to institute proceedings in an unjust enrichment way. When the two methods are grouped together, the more flexible approach provided in Article 9: 903 of the European Principles of Contract Law can be applied. The main content of the fifth part is the limitation on the right of return of the non-defaulting party, that is, the defaulting party can not request the defaulting party to return it in all four cases although it performs part of its performance or imperfection. In the final conclusion of this article, I think that as a manifestation of the principle of fairness, the defaulting party should enjoy the right of return when its performance value is greater than that of the other party for breach of contract, and should adopt the principle of European Contract Law 9: 903 The methods provided for in order to fairly protect the interests of the defaulting party.