On May 31, 2017, the Plaintiff is a public corporation established by the merger between Seoul metro and Seoul Metropolitan Government Urban Railroad Corporation, and one to eight subway lines in the Seoul Metropolitan Area.

The integrated transit discount system between public transport means a system that applies the fare on the basis of the total distance of use when passengers use the means of transport, such as buses and electric iron consecutively within a certain period of time. On July 1, 2004, it was first implemented on the transfer between electric rail and Seoul bus in the Seoul metropolitan area.

On June 8, 2007, the Seoul Special Metropolitan City, the Seoul Metropolitan City, and the Korea Railroad Corporation agreed to implement the integrated transit discount system with the application of the Seoul Metropolitan Area electric railroad, Seoul bus, and Gyeonggi bus, and in particular, as to the burden of charge reduction (hereinafter referred to as the "transfer loss amount") arising from the transfer discount, etc., the Seoul Gyeonggi-do Joint Agreement on Railroad for the Implementation of the Seoul Gyeonggi-do Integrated Transit Approval System for Public Transport in Seoul (hereinafter referred to as the "Agreement in this case"), and the main contents are as follows:

(2) The Seoul Special Metropolitan City, the defendant, and the Korea Railroad Corporation agree to implement the "integrated transit reduction and exemption system in Seoul Metropolitan Area" (hereinafter referred to as the "integrated rate system") for the enhancement of traffic convenience and the promotion of public transport in the Seoul Metropolitan Area as follows:

Article 2 (Subject-Matter) The integrated fare system shall apply only when a person continues to use the following means of public transportation by means of transportation cards:

(1) Seoul bus: A line, branch line, circular or village bus under the direction and supervision of the Seoul Special Metropolitan City Mayor. (2) Gyeonggi bus: A general urban bus and village bus among route buses under the direction and supervision of the Gyeonggi-do Governor.