This paper aims at analysing the ideological, political, and legal background of urban planning on the basis of empirical research on the rezoning of industrial sites in Balmain in Sydney, which has become a contentious issue in recent years. Balmain became a test for the state government policy on urban consolidation. The rezoning in Balmain became a major issue because several giant corporations (Monsanto, Caltex, Unilever, and Balmain Power Station) were involved, with the approval of state government of NSW, against the residents groups and local government of Leichhardt. The state government, the council, the developers, and the residents have been fighting for the right to decide the case. It is interesting to examine in what legal based the laws, the ideological, and political contested on the urban planning. This chapter will analyse a structure of the urban planning from the legal perspective and the theory of the social function of urban planning in Sydney generally, and in some detail will ers to the Balmain case.