在半總統制體制下的我國總統，是一位實權的國家元首，位居憲政運作的中樞，但學術界對於總統在法案推動上角色和行為之研究非常少見，使得吾人對於總統在立法和政策決定的實務行為之了解較為有限。本文以陳水扁總統執政時期之經驗為例，探討總統對法案表達支持的態度之行為，藉此了解憲法正式條文和制度之外其實際憲政角色。本文首先系統性地蒐集陳總統曾經表達過態度的法案，歸納偏好表達的場合或機制類型，並分析不同機制下的偏好強度。藉由上述問題的探索，以提供了解實務上我國半總統制下總統的立法推動行為，並補充既有文獻的不足。

The president under Taiwan's semi-presidentialism is not a ceremonial head of state. On the contrary, he or she has considerable powers and is the head of the political system. However, until now, there is rare study exploring the president's role on the process of law-making, making us know very little about his decision-making behavior. This study tries to explore the behaviors of President Chen Shui-bian on the process of law-making in 2000-2008, to improve the understanding of the role of the president beyond the words and design of the formal constitutional structure. The paper systematically explores the President's preferences of all important bills, and analyzes the mechanisms of the preference-making and the strength of his preference on each bill. Based upon these findings, we could realize more about the role of president under Taiwan's semi-presidentialism. And author wish it will supplement deficiencies of the existing literature.