本文是以我國第七屆立法委員的選舉制度為主要研究範圍。2005年6月7日國民大會複決通過第七次修憲增修文,規定我國立法委員的選舉自第七屆起,改採「單一選區兩票制」。本文的研究重點主要分為兩個部分,第一部分是關於選舉制度設計的探討,從議會規模、立法委員的產生方式及選區劃分的爭議,來說明我國單一選區兩票制的內容及特性。第二部分則是針對「單一選區兩票制」的實施結果,嘗試歸納出新選舉制度對我國可能產生的政治效應,並依此驗證杜弗傑法則。此外,並結合德、日實施「單一選區兩票制」的經驗,作為我國未來選舉制度修正時的參考。「單一選區兩票制」在我國首次實施,對於政黨政治的影響並非定論,僅能就選舉結果看出部分端倪,從研究結果,約可歸納出三點研究發現,也基本印證了杜弗傑法則的理論:(一)國會中形成兩黨競爭的局面(二)有助於黨紀的維持,促進兩黨向心競爭的趨勢(三)兩大黨之外的「第三勢力」均呈現泡沫化
In 2005, Taiwan reduced the number of legislative seats to 113 and changed its legislative electoral system to mixed electoral systems combining single-member districts and proportional representation. It is also called ”combined-independent system” being implemented in Japan, Russia, and Italy. In this system, the votes are counted separately in both types of seat so that the share of the vote for each party cast in the party lists is unrelated to the distribution of seats in the single-member districts. In this article the authors discussed the electoral systems, party systems, proportion of votes to seats, political landscape and legislative system. According to the consequences of the Legistative Yuan election in 2008, There were three points concluded in this thesis. First, the party system of Taiwan changed from Multiple Party System into Two-Party System. Second, the party discipline was enforced and contributed to the development of two-party competition. Third, Combined- independent system squeezed the chance for small party to survive in the local political arena.Additionally, the authors made some suggestions for the improvemet of combined-independent system in the future by the approach of historical institutionalism.First, the threshold should be set slightly lower. Second, the total number of parliamentary seats was suggested to be increased. Third, the seats of Proportional Representation could be added. Fourth, the government could provide financial support for political parties to hold a primary election.