釋字第 509 號藉由轉化刑法誹謗罪之文義，以限縮誹謗罪成立之 空間，調和言論自由與個人名譽間之衝突，而達到保障言論自由之目 的，該號解釋在我國言論自由之發展史上，顯然具有重要意義。 然而該號解釋在做成後亦衍生出諸多疑義，本文第一章概述之；其中該號解釋所謂：「行為人有相當理由確信其為真實者」，是否即為美國法上之「真正惡意原則」，爭議已久，本文考量我國刑法之固有體系，認為「合理查證原則」始為該號解釋之正解，於第二章中將為解析；為達憲法保障言論自由之目的，釋字第 509 號之意旨是否得類推適用於民事事件？本文立於民刑事「實體法」與「訴訟法」基本結構不同之認知下，採取肯定看法，此見於本文第三章；而釋字第 509號對於言論自由與名譽權之調和案件，並未闡明其類型區分，而本文認為我國實務應有更細緻之類型化操作，此於第四章探討之。 總結前述各章內容，本文認為目前實務對於言論自由與名譽權調和案件之處理上不盡合理，故將案件依所涉不同之「人物」與「事項」，區分為民事法及刑事法各四種不同類型，參酌大法官解釋、學者見解及比較法上判決，於第五章提出本文之處理方式。
As our country’s democracy transits, Interpretation No.509 obviously has a significant position in the history of the development of freedom of speech in Taiwan. This Interpretation was elaborated by transforming the meaning of the criminal law of defamation provisions, by reconciling the conflict between freedom of speech and personal reputation,and by lessening the defamation provisions in order to achieve the purpose of protection of freedom of speech. However, this Interpretation has been derived into many issues that chapter one will introduce. One of the disputes of this Interpretation was this sentence:“as long as the accused has reasonable grounds to believe that the statement was true when disseminated and has proffered evidence to suppose the belief, the accused must be found not guilty of criminal defamation.”Did the meaning of this sentence equal to the doctrine of“actual malice”in America’s laws of defamation? I think this Interpretation has adopted the doctrine of reasonable investigation. In chapter two I will analyze this. In chapter three, I will compare the different structures between civil law and criminal law to discuss whether the Interpretation No.509 can be applied to tort of defamation in order to protect freedom of speech. Interpretation No.509 did not clarify the sort for those cases that reconcile between freedom of speech and reputation , but I argue that courts should have manipulated cases by classification, presented in chapter four. Summarizing the preceding chapters, I believe that the current practice for operating cases of reconciling freedom of speech and reputation are not quite reasonable, so I will divide civil law and criminal law cases into each of four different types and put forward approach in chapter five.