| As a unique system of civil law countries, the system of unstable counter-argument right has had an important influence on Contract Law of many countries. In heterochronia performing contracts, it is used as a means for the party who is to perform first to reject the demand of the party who is to perform later to promote the performance of contract, prevent fraud, protect legal intrest of the former and to maintain market order.In China, the system of unstable counter-argument right has been stipulated in Contract Law 1999. Based on traditonal theory of civil law countries, it absorbs the rationality of anticipatory breach of contract system in common law countries, forms a system with Chinese characteristics and improves the traditonal system. Therefore, Chinese Contract Law conforms with the histroric trend of merging two major legar systems in the world and reflects our remarkable success. Howerver, there are still some defects of the legislation. For example, it does not coordinate with the two systems of anticipated breach and unstable counter-argument right, confuses legislation and leads to chaos of legal performance.Besides the part of preferance and conclusion, the thesis concludes four parts.Partâ… Genernal Theory of the system of Unstable Counter-argument Right. I first introduce the concept and legal source of the system of unstable counter-argument right. The system originates from German and is absorbed by more and more civil law countries. Then I analyse its theoretical basis and regard that honesty, good faith, safety and interest are values we seek. As to nature of the system, I think the right is one against right of claim.Partâ…¡Components and Legal Effects of Unstable Counter-argument Right. As to its components, I introduces the different opinions of traditional civil law and Chinese Contract Law. Then I analyse its legal effects according to the theory of civil law countries as well as the stipulations in Chinese Contract Law.Partâ…¢Comparision of System of Unstable Counter-argument Right and Anticipatory Breach of Contract system. Firstly, I intruoduce the leagal source and characteristics of anticipatory breach of contract system in common law countries. Corresponding to the former in civil law countries, the latter system is established in cases. Then I analyse their differences and common features.Partâ…£Application and Improvement of Chinese System of Unstable Counter-argument Right. I introduce its legal source and current stipulations in Chinese law, analyse its features and defects and provide my opinion on how to improve the system. |