合理使用作為喘息空間，卻在判斷上充滿著不確定性，移植美國著作權法第107條之我國著作權法第65條第2項亦如此，因此，本文擬從實證方法看合理使用判決結果、各款判斷基準與各判斷因素間之關係，發掘實務上影響各款判斷基準的關鍵判斷因素以及合理使用判斷結果的關鍵判斷基準。本文發現：我國法院仍以商業與非商業二分法為第一款判斷基準之依歸；第二款判斷基準的運用，若改為著作類型進行判斷，反而比著作物性質之認定更為法院所用；第三款判斷基準之結果主要受質量比例與整體著作範圍判斷的影響，不過值得注意的是，法院計算取用比例多寡時，偶有誤用分母而造成判斷失準之結果；至於影響第四款判斷基準最主要的要素則為侵權著作未來散布過大的可能性。若從法院使用的情形來分析，我國並未只對第一款及第三款判斷基準為關注，第四款判斷基準也有其影響性，尤其是其與第一款判斷基準的連結關係：一、第四款判斷基準受第一款判斷基準結果所影響而與其判斷要素間的連結與既定規則不同；另，不論是智財法院、地方法院或是高等法院都有未為四款判斷基準完整審查的情形，究其原因除了高等法院受其審級及前審的影響外，主要還有第二款判斷基準與合理使用結果連結性過低的情形等。

As a ”breathing space”, the scope of fair use is uncertain to prohibit the spillover effect of copyright. In this empirical study, we will explain and verify how the fair use doctrine used in Taiwanese legal system. The perplexity occurred when the Section 107 of the U.S. copyright law was transplanted into Article 65 (2) of Taiwanese Copyright Act years ago. Even though rules were clearly announced by the authority body, it could not be assured the courts would follow the rules. As the the myth goes ”Leniency to those who confess their crimes and severity to those who refuse to”, it was not true in some empirical analysis.Reviewing the four-factor test, the courts prefer to interpret the first factor as the question of whether it was commercial use. In the second factor, because it was difficult to define ”the nature of the work”, the courts prefer to replacing with ”the category of the work”, making it easier to operate and predict. The third factor, the easiest one to sentence judgments, has usually been ignored when examining so-called ”the core value of the work”. Meanwhile, the courts may misapply denominators in the review of this factor in some cases. For the fourth factor, the courts mainly focused on whether the infringing product or work may spread around in the the market. In practice, the courts usually announced rulings on not only the first and third factors but the fourth, tightly joining with the first one. To our supprise, the interaction between the fourth factor and its elements recognized by the courts was different from the rules. This appearance might be resulted from the outcome of the first factor examination. In short, even though the courts literally examined four factors to decide the scope, they did not follow in real, probably resultig from the difficulty of interpreting the second factor.Since fair use concept is a tradeoff between flexibility and certainty, the localization of the four-factor test shall be thoroughly considered. Back to the legislative history and the spirit of fair use, obviously, the better solution would be to give more time and space for the Supreme Court to mold prejudications for lower courts to use the test first.