Abstract: One of the conundrums in state-building is that the state must not only have sufficient capacity to defend its territory, enforce laws, and maintain social order, but at the same time, its actions must be regulated. In theory, two mechanisms have been proposed to address this problem:horizontal-mutual constraint and vertical-mutual constraint. The horizontal-mutual constraint refers to the horizontal separation of power within the same level of government, such as the separation of legislative power, judicial power, and administrative power, to form a relationship of checks and balances. The vertical-mutual constraint refers to a mutual relationship among central supervision, local governance and social accountability to constrain the power of the central and local governments, especially of the latter, through the hierarchy of division of powers from the central government to local governments and lastly, the society. In China, the horizontal-mutual constraint mechanism is hard to be functional because of the centralized Junxian system. However, the multi-level governance structure derived from the centralized Junxian system offers China the possibility of adopting the vertical-mutual constraint mechanism. Thus, for China, how to construct a vertical-mutual constraint mechanism and how to adopt the mechanism are the major concerns of state-building and state governance. Historically, Chinese scholars have made systematic studies of these issues. The direction of their exploration is to construct the relationship between the state and society based on the concept "Mandate of Heaven"(tianming) and expand it into mutual constraints between the central government, local governments and society. The significance of this exploration is that it reveals two important conditions for the full functioning of the vertical restraint mechanism. One is the separation of government and governance, and the other is the separation of dominion and administrative authority, in so doing it forms a mode of combining centralized government with decentralized administration. This paper characterizes this mode as the vertical-mutual constraint system.

Key words: Junxian system, centralization, decentralization, horizontal-mutual constraint mechanism