The defendant's appeal is dismissed.

1. Summary of grounds for appeal by the defendant;

A. Fact-misunderstanding [the charge of this case, which is against the Act on Special Cases Concerning the Punishment, etc. of Sexual Crimes (Use of Cameras, etc.)] is a legitimate act that does not go against social norms, since the defendant established a camera at the inside of the house where the defendant resides for the purpose of discovering circumstances to suspect the victim's misconduct and securing a critical evidence.

Nevertheless, the lower court found the Defendant guilty of this part of the facts charged, thereby misunderstanding the facts and adversely affecting the conclusion of the judgment.

B. The judgment of the court below that sentenced the defendant to a fine of 4,000,000 won and the order to complete a sexual assault treatment program for 40 hours is too unreasonable.

2. Determination

A. The "act which does not violate the social rules" under Article 20 of the Criminal Act as to the assertion of mistake of facts refers to the act which can be accepted in light of the overall legal order or the social ethics or social norms surrounding it. Whether certain act is a legitimate act that does not violate the social norms and thus, it should be judged individually by considering and determining the illegality individually under specific circumstances. Thus, in order to recognize such legitimate act, the following requirements should be met: (i) legitimacy of the motive or purpose of the act; (ii) reasonableness of the means or method; (iii) the means or method of the act; (iv) balance between the benefits of protection and infringement; and (v) supplementary nature that there is no other means or method other than the act (see, e.g., Supreme Court Decision 2002Do5077, Dec. 26, 2002). The court below rejected the defendant's assertion on the grounds that the defendant's act was established for the purpose of detecting the victim's unlawful act as alleged in the grounds for appeal.