This article tries to analyze the New Frankfurt school's theory of justice and its relation to the law, in order to clarify, how the discourse of justice contributes to the evolution of the legal system. The New Frankfurt school receives Luhmann's system theory and develops a new concept of justice: Justice is not the absolute transcendent canon of law, but the irritation of operations in the legal system. Justice forces the operation in social legal subsystem to take its environment into account. The integrity of mind and pains of body, which is the environment of social communicative system, can reenter the communicative legal and political system by the discourse of ”human rights” and ”justice”. This process of ”re-entry” gives the reason to reform the given conditions of the law, and in this way prompts its evolution.