On December 17, 2015, the Seoul Central District Court gave a verdict of not guilty to Tatsuya Kato, former Seoul bureau chief of Sankei Shimbun. He had been charged with defaming South Korea’s President Park Geun-hye. The purpose of this study is to analyze the decision and examine suggestions for the defamation laws in Japan and South Korea. Although I agree with the conclusion of the decision, I cannot accept the part of verdict on defamation of Park as a private figure. Structural problems exist in South Korea’s defamation laws, and the criminal prosecution of this case deviates from the international standards. Therefore, it is natural that the United Nations has repeatedly recommended that the South Korean government abolish criminal defamation. South Korea has to fundamentally reform the criminal defamation law, which has suppressed critical speech. Meanwhile, this case has considerable implications for Japan, where criminal defamation is being applied. Japan should also join the international community in pursuing abolition or a strict application of the criminal defamation law as it has harmful effects on democracy as well as freedom of expression.