多數後共國家從上個世紀末展開民主轉型，迄今已經將近20餘年。在轉型初期，首要的議題之一就是憲政工程的搭建，多數後共國家在類似的背景下設計了半總統制的憲法架構。由於半總統制是一個權力容易擺盪的體制，因此實際的憲政運作仍舊存在多變的可能。這段時期以來，有些後共國家已經運作出準議會制的憲政秩序，有些仍然在總統與國會的二元架構中進行權力競逐。影響憲政運作的原因很多，例如政黨體系、制度設計、政治菁英的選擇等。追根究底，轉型初期的社會結構是不能被忽略的上游因素。本文以羅馬尼亞為例，討論原子化社會下的民主轉型，對於菁英延續、政黨體系建立的影響，並以此解釋憲法設計乃至於憲政運作的特性。本文認為，原子化的社會使得舊有政治勢力容易延續，強勢總統搭配分歧國會是民主化後憲政運作的起點。若要進行體制的轉型，政黨體系的變遷以及制度的修改，是必須相互搭配的條件。

Most post-communist countries have experienced democratization since the past two decades. And to start democratization, many of them have adopted a semi-presidential constitution. However, in the practice of semi-presidentialism, we often observe that the operation of semi-presidential system in these new democracies were unstable and variable. For example, some post-communist countries have become the quasi-parliamentary democracies; the others are caught in the dual executive between the president and the parliament. Their experiences show that the orientations of semi-presidentialism are conditioned by party system, the design of the constitution, and also by the political elites. In other words, the key of the orientations lies in the social structure of one country. This paper will focus on the constitutional design of Romania and discuss how democratization in the atomized society influences the ecology of the political elites and the construction of the party system in Romania. Furthermore, this paper hopes that such discussions can enrich our understanding of constitutional institutions and operations. This paper intends to argue that the atomization of society enables the old establishments and powers from communism to continue, creating powerful president conditioned by divided parliament. And to alter such unbalanced relationship, Romania not only needs to change its own party system but also to revise the constitutional institution.