民事訴訟法於 2003 年修訂時，於第 56 條之 1 增設「命強制追加為原告」之程序機制，以解決當部分固有必要共同原告拒絕起訴時，影響其他原告提起訴訟之權益的問題。此項程序機制之增設，雖有助於欲起訴主張權益人之訴訟權保障，惟亦引發諸多在理論上難解之問題。本文旨在藉由收集、解讀法院之裁判，以實證之角度，考察實務上就此機制之操作，並對涉及之相關爭議問題，進行檢討分析。本文發現，目前適用此程序機制之實際案例，全部均集中於涉及公同共有物之紛爭脈絡，在全體公同共有人間，就是否提起訴訟產生爭執；此外，法院就各式拒絕起訴理由之主張，僅肯認「利害關係衝突」構成正當理由；最後，法院在裁判中之論理，呈現其尚未能充分掌握此程序機制之生澀，而僅能由立法理由中有限之指示，對法條進行機械性之形式詮釋。以實證考察之結果為基礎，本文一方面藉由比較法考察所得之啟 示，提出基本之理論架構與解釋向度，一方面針對本程序機制於未來之運作，提出筆者的建議並為初步之展望。

The 2003 Amendment of the Code of Civil Procedure in Taiwan introduced a new procedural device—the involuntary plaintiff—by means of which the suing plaintiffs can compel other indispensable but unwilling parties to join as co-plaintiffs. Although this device helps to resolve the problems faced by the suing plaintiff when other indispensable plaintiffs refuse to initiate the litigation together, it at the same time raises many difficult questions and causes certain controversies. This article purports to examine the problems surrounding the involuntary plaintiff device from an empirical perspective and then proposes a theoretical framework. Specifically, this article collects all available court decisions regarding the application of this device and summarizes the common features and questions appeared in these cases. Based on the empirical results, this article criticizes that the courts are quite amateur about the device and do not grasp its essence. Therefore, the author establishes a basic theoretical framework to explain how the device should be applied and interpreted to meet the practical needs. The author further provides his own prediction with regard to how the device would continue to evolve in the future.