Quasi-contract rooted in the roman law,and was inherited by the civil law and the common law,but there are many differents in the quasi-contract between the civil law and the case law.
准契约起源于罗马法，后被大陆法系和英美法系所继承，但各自继承和发展的内容又不一致。
By virtue of the theory of quasi-contract in Roman law,we can not only explain the obligation conveyance under the situation of issuing bill of lading,but also solve the problem on how to determine the litigation right in legal practice.
借助罗马法中的准契约理论,既能对提单下的义务转让进行合理解释,也能解决在实务中诉权的确定之难。