1. The defendants' appeal is dismissed.

2. The motion for intervention by the Intervenor joining the Defendant is dismissed.

3. Appeal.

1. The reasoning of the court's explanation as to this case is as follows, except for the addition of the decision on the application for intervention by the supplementary intervenor to the defendant joining the court of first instance, and therefore, it is consistent with the reasoning of the court of first instance under the main sentence of Article 420 of the Civil Procedure Act.

2. Determination as to whether the motion for intervention by the Intervenor joining the Defendant is legitimate

A. The Intervenor joining the Defendant, as the lessee of the instant building, was brought a lawsuit claiming reimbursement from the Plaintiff as the Plaintiff, and the relevant case is dismissed in the first instance trial on the ground that the Plaintiff was not a party to the lawsuit, and is still pending in the final appeal at the second instance after the dismissal of the appeal. As such, the Intervenor joining the Defendant asserts that there is a legal interest in the outcome of the instant lawsuit.

B. In order to intervene in an assistance to assist one of the parties in a specific litigation case, there must be an interest in the outcome of the relevant lawsuit, and the term "interest" refers to a legal interest, not a de facto, economic or emotional interest, and the existence of such interest refers to a case in which res judicata or executory power of the relevant judgment is obtained as a matter of course, or a case in which the legal status of a person who intends to participate in an assistance is determined at least on the premise of the relevant judgment, even if the effect of the relevant judgment does not directly affect

(see, e.g., Supreme Court Order 2014Ma4009, May 29, 2014). However, as alleged in the foregoing, the circumstance that the Defendants lost in the instant lawsuit may have an impact on the outcome of the instant lawsuit is nothing more than a de facto interest and does not constitute a legal interest in the outcome of the instant lawsuit. Therefore, the Defendant’s motion for intervention in the Intervenor’s Intervenor’s Intervenor’s motion for intervention did not meet the requirements for intervention.