Reasoning Ⅰ. Overview of the Case A. 2016Hun-Ma388 1. Complainants are users of the telecommunications service provided by telecommunications business operators, Companies A, B, and C. 2. In accordance with Article 83, Section (3) of the Telecommunications Business Act, Respondents asked Companies A and B to provide for investigation the “name, resident registration number, address, phone number, date of subscription” of Complainants J.S., K.J., C.Y., K.M., H.J., A.H., P.C., Y.S., and L.G. described in Appendix 3, and the above telecommunications business operators provided Complainants’ communications data as described in Appendix 3 to Respondents. Through this, Respondents obtained the communications data of Complainants listed in Appendix 3 from May 21, 2015, to March 4, 2016. In addition, Respondents, prosecutors belonging to prosecutors’ offices at each level, and the heads of investigative agencies requested Companies A, B, and C to provide communications data of Complainants other than those listed in Appendix 3 and obtained their communications data. 3. In response, on May 18, 2016, Complainants filed the constitutional complaint in this case against Article 83, Section (3) of the Telecommunications Business Act which stipulates when a prosecutor, the head of an investigative agency including the head of a prosecutor or military investigative agency, or the head of an intelligence investigation agency (hereinafter referred to as “the investigative agency et al.”) requests the telecommunications business operator to provide communications data, the telecommunications business operator may comply with the request, while Complainants listed in Appendix 3 filed - 22 -