日本民主黨於 2009 年的眾議院選舉中擊敗執政的自由民主黨，黨魁鳩山由紀夫於 9 月 16 日成為日本首相。由於民主黨在參議院未過半，為了維持國會穩定運作，鳩山首相選擇與社會民主黨、國民新黨組成聯合內閣。 不過鳩山政權內部不斷出現閣員之間的對立，而鳩山首相始終無法處理這些政府決策過程之中所發生的混亂，學者與主要媒體多認為，發生混亂的原因是在於鳩山本人的領導能力不足。不過本論文認為，導致鳩山政權內部的混亂主因是民主黨建構的決策運作模式本..

Yukio Hatoyama, the chairman of the Democratic Party of Japan (DPJ), succeeded to the Prime Minister of Japan on 16 September 2009 after DPJ won the 2009 Japanese general election. In the election, DPJ acquired 308 out of a total of 480 seats in the House of Representatives of Japan, while the Liberal Democratic Party(LDP), the former ruling party only acquired 119 seats. However, Hatoyama was thus forced to form a coalition government with the Social Democratic Party and the People’s New Party in response to a situatio..