本文以總統任命權為制度基礎，分析台灣在一致性政府與分立政府時期，總統與行政院院長的互動關係，以及所影響的半總統制運作。在台灣半總統制經驗中，由於總統掌握完整閣揆任命權，使得行政院院長往往被認為是總統的「執行長」，不過，在1997年至今一共12位閣揆的憲政經驗中，總統是否能確保閣揆的執行長化？或者，閣揆是否有和總統爭奪行政主導權之可能？配合閣揆行動考量、總統立場、政治局勢變遷等因素，仍存在諸多討論空間。本文彙整歷任行政院院長任內與總統互動之舉措，以及上、下台原因，論述這12位閣揆在一致性政府或分立政府時期的角色和當中的行政權運作模式，本文認為，半總統制研究中的「府院關係」，以及閣揆角色受限或突破，將是半總統制能否實踐憲政民主的重要關鍵。

The semi-presidential system has been operated for 20 years in Taiwan. This paper will base on design and operation of the executive power of the constitution of Taiwan, ground on the theory of ＂Path Dependence,＂ and carry on cause and effect analysis according to the historical context. In the viewpoint of historical institutionalism, this paper not only pays attention to the context of constitutional history but emphasize the actions of relative actors in this history to probe what is constrained by the institutional structure is also the possibility to change it. By pointing out the path dependence of premier's role in Taiwan (1997-2016), we shall conclude the President of the Executive Yuan is the key person to advance our constitutional system.

半總統制;行政院院長;總統;行政權;路徑依賴

Semi-presidential System; President of the Executive Yuan; President; Executive Power; Path Dependence