本文主要利用雷震手稿所保存的《向毒素思想總攻擊》與《「自由中國」半月刊違法言論摘要》。兩份清楚呈現國民黨當局言論尺度的文本，以及國史館出版的《雷震案史料彙編》，分析雷震案的言責問題，並探討其所突顯的1950年代的言論自由問題。早在1950年代初期，蔣中正與蔣經國在言談中便將雷震的主張及《自由中國》的言論，與「匪諜」連結在一起。至1958年，警備總司令部更進一步提出將雷震逮捕究辦及關閉《自由中國》的主張，但因有權管理者見解不一而延宕下來。1960年蔣中正總統決定逮捕雷震，使該案成真。一開始執政當局將焦點擺在《自由中國》的言論上，但隨即因各界反彈而轉向。從行政機關內部討論的資料可知，無論以哪種罪責為雷震定罪，皆有可議之處，而國民黨對此知之甚詳。再者，能否輕率的以幾篇文章判處重罪，蔣中正對傅正與對雷震，顯然有不同的看法。雖然，國民黨決定抓人與雷震籌組反對黨有絕對的關係。但不可諱言的，《自由中國》的言論顯然是蔣中正的心中刺，甚而需要在起訴書中留下其對相關言論的批判。

This paper explores the KMT's accusation against Lei Chen and the plight of press freedom in Taiwan. In the early 1950s, Chiang Kai-shek and Chiang Ching-kao had already claimed that the comments of Lei Chen and ”Free China” were similar with those of ”Communist agents” (匪諜). In 1958, the Taiwan Garrison General Headquarters made two proposals to deal with the matter. The first was to arrest Lei Chen and the second, to close ”Free China”. But these proposals were not carried out because of internal differences in the KMT. Instead Lei Chen was arrested in 1960 on Chiang Kai-shek's order. At first, the ruling authorities put the focus on the comments of ”Free China”, but soon retracted because of public pressure. Intelligence agency and Chiang Kai-shek's aides then proposed three kinds of crime and sentence respectively. But all were difficult to defend and the KMT knew clearly. In dealing with two different defendants Lei Chen and Fu Zheng in the same case, Chiang Kai-shek had different answers as to whether or not to give a heavy sentence just because a few articles. Although he decided to arrest Lei Chen not just because of his comments of Lei Chen and ”Free China”, Chiang Kai-shek amended the indictment personally and criticized those opinions nonetheless. Obviously, the comments of ”Free China” were so uncomfortable to Chiang that it was allowed to exist any longer.