Collateral Obligation Legal Issues

In traditional theory of contract law obligation is according to regulation by law and engagement by the parties, except which there is no any obligation'or liability between the parties. However, the expansion of obligation which is a challenge to traditional contract law has been a trend in the development of contract law.The introduction of collateral obligation is a reformation of traditional contract law. The parties should performance not only obligation which is regulated and engaged, but also necessary obligation of good faith, which is called collateral obligation. There are a lot of problems which are confused on the theory of collateral obligation because of its long history of development. The author is trying to make the theory clear by comparing with other's viewpoints in the article. There are also some viewpoints posed here.The theory of collateral obligation is changeable, so the rule of development must be obeyed in the study. As Homes, the associate justice of American Supreme Court said, in order to know what the law is we must know what it was and what it will be. However, the research on the theory of collateral obligation now is often limited in the field of contract law and the development of collateral obligation is ignored. So there are also some discussions about the development of collateral obligation.