This article reviews the reasonableness of the Seoul Central District Court decision 2020na81375 issued on October 8, 2021 (hereinafter referred to as the court of original instance) where the issue was whether a remark by Youtube content creators (defendants) on a Youtube channel regarding a public official (plaintiff) constitutes defamation and if defamation is found, whether there are grounds to preclude the illegality of the defendants' act. This article also reviews the reasonableness of the Supreme Court decision 2021da285465 issued on July 14, 2022 (hereinafter referred to as the Subject Decision) which adjudicated on whether the cause of appeal by the defendants (including the argument that the court of original instance misunderstood the legal principle of defamation against a public official) constitutes proper grounds for appeal under the Trial of Small Claims Act. For the review, this article conducts research in the following sequence. As a basic work to review the validity of the defendants' grounds for appeal, including the argument that the court of original instance misunderstood the legal principle of defamation of a public official, along with the discussion of the academic theory of the legal principle, which will help resolve the legal question in the case here, among the general legal principles in the precedents which addressed defamation (including the precedents which adjudicated on the meaning of reputation and defamation and the grounds to preclude illegality), I reviewed the Supreme Court decision on tort liability based on defamation of a public official (a politician), in a situation which is the same as or similar to the case here. Based on this work, I reviewed the validity of the decision of the court of original instance as to whether tort liability based on the defamation of the plaintiff may be found in the defendants' remark. Finally, it is reviewed as to whether the defendants' grounds for appeal in this case were reasonable grounds for appeal under the Trial of Small Claims Act. As a result, it is argued in this article that the conclusion of the court of original instance is not reasonable, which ruled that the defendants' remark amounts to defamation of the plaintiff, but found the grounds for precluding the illegality and denied the tort liability for the defendants based on defamation against the plaintiff. It is also argued that the Subject Decision is reasonable, which held that a cause of appeal under Article 3(2) of the Trial of Small Claims Act is not found in the defendants' grounds for appeal. It was held that the defendants' grounds for appeal do not constitute a cause in Article 3(2) of the Trial of Small Claims Act. As a result, the defendants' tort liability for defamation of the plaintiff was recognized as in the decision of the court of original instance, but regrettably, the Supreme Court did not adjudicate on this issue. This is because the Supreme Court has an important task of adjudicating the fundamental question of effectively interpreting the conflict or tension between freedom of expression and protection of personal rights, as well as clarifying how the review standards relaxed in a public sphere or the legal principle of malicious attack, which recognized in the precedents, applies specifically to a public figure such as the public official in this case. However, the question was not addressed in the Subject Decision. Hopefully, this article will result in a more in-depth discussion on the issue of defamation of public officials in subsequent rulings.