Therefore, even if the above defendant assaulted the police officer, he cannot be punished as a crime of obstructing the performance of official duties.

② Furthermore, the Defendant did not know that he was a police officer in the process of performing official duties, and there was no intention to obstruct the performance of official duties.

Nevertheless, the lower court erred by misapprehending the legal doctrine, thereby finding the Defendant guilty.

2. Determination

A. The crime of interference with the performance of official duties is the premise of a legitimate performance of official duties by a public official. To be lawful, the act is not only within the abstract authority of the public official in question, but also within the specific authority. Whether the execution of official duties by a public official belonging to abstract authority is legitimate should be determined objectively and reasonably based on the specific circumstances at the time of the act, and it should not be determined ex post facto in pure objective criteria (see Supreme Court Decision 91Do453 delivered on May 10, 1991). The duties of a police officer are not limited to a criminal investigation, but also are limited to the prevention and suppression of a crime and the protection of people's lives and property (Article 2 of the Act on the Execution of Duties of Police Officers). Accordingly, a police officer may take proper measures, such as protecting the police officer in the case of a person who is likely to harm his or other people's life or body, due to alcohol, and protecting the police officer in the case of a person who was under influence of alcohol (Article 4(1) of the Act).