In cases where it is evident by objective circumstances that an investigator informed the suspect that he/she may refuse the accompanying of the suspect prior to the accompanying while accompanying the investigative agency, etc. in the course of investigation, or that the suspect who was aware that he/she could freely leave the accompanying place at any time, was accompanied by the suspect's voluntary will, such as where it is acknowledged that the suspect could have been accompanied by the investigative agency, etc., the legality of accompanying is recognized (see, e.g., Supreme Court Decisions 2005Do6810, Jul. 6, 2006; 2012Do8890, Sept. 13, 2012). Furthermore, determination of the foregoing voluntary accompanying should be based on objective circumstances, comprehensively taking into account various circumstances, such as the time and place of accompanying, the method and method of accompanying, the existence of the suspect's intention to refuse accompanying, the method and existence of the intention to leave after accompanying,

(see, e.g., Supreme Court Decisions 93Da35155, Nov. 23, 1993; 99Do4279, Jan. 30, 2001). Meanwhile, the crime of non-compliance with a alcohol measurement under Article 148-2(1)2 of the Road Traffic Act is established when a person with considerable grounds for recognizing that a person under the influence of alcohol refuses to comply with a police officer’s measurement under Article 44(2) of the same Act.

In light of the provisions of Article 44 (2) of the Road Traffic Act, if there are reasonable grounds to recognize that a driver has driven a motor vehicle while under the influence of alcohol and it is necessary to confirm whether a driver has driven a motor vehicle, etc., then it is evident that a police officer cannot confirm whether a driver has driven a motor vehicle by means of an ex post facto alcohol test, unless it is clear that a police officer may request a driver to measure the alcohol, and if the driver fails to comply with it, the crime of non-compliance with a alcohol test under Article 148-2 (1)

Supreme Court Decision 196No. 1000 delivered on June 13, 1997