歷經19年，自由軟體運動漸成長為程式開發中不可或缺的一部分。企業與公司積極採用自由軟體，因為採用它們效能穩定且經濟實惠。然而自由軟體是「自由」而非「免費」的。大部分的自由軟體以Gnu General Public License授權予公眾，此授權契約附有互惠條款，當被授權人滿足特定條件時，則須負擔互惠義務。若被授權人未盡互惠義務時，可能會導致侵害著作權的結果。在大部分的情況下，是否須負互惠義務是相當清楚的。然而，有些邊際案件，大部分涉及程式間交互運作，則不容易判斷。本論文經研究互惠義務條款、自由軟體基金會（Free Software Foundation, FSF）的問答集與其他官方文件、以及交互運作採用之技術，提出檢驗互惠義務是否成立之判斷流程。最後，本論文擇一與GPL'd程式交互運作產生互惠義務爭議的案件，利用前述判斷流程檢驗之。

19 years after its debut, Free Software has grown from an evangelist's movement into a critical part of software development. Firms and companies are eager adapters of free software, which boast modest price and robust stablity. However, free software are free as in freedom, not price. The majority of free software are licensed under Gnu General Public License, which implements a reciprocal clause, and requires certain obligations from licensees once they meet its criteria. Negligence of obligations may result in copyright infringement. In most cases, licensees can easily determine whether the criteria are met. Nevertheless, there are quite a few difficult boarderline cases, mostly involving interoperation of softwares. By studying the reciprocal clause, FAQs and other official statements from the Free Software Foundation, and underlying technology, this paper has developed a flowchart for determining whether obligations are due. Finally, this paper carefully selects a boarderline case that involves interoperation with GPL'd software, and analyize it with the flowchart.

小泉修（ 2007） ，學會程式設計的原理與技術， 周明憲譯， 博碩文化。
羅明通（2004） ，著作權法論， 台英國際商務法律事務所。
蕭雄淋（2005） ，著作權法論， 五南出版社。
謝銘洋等（ 2005）， 著作權法解讀， 元照出版社。
賴文智，王文君（ 2007）， 數位著作權法， 益思科技法律事務所。