1. The instant lawsuit shall be dismissed.

2. The costs of lawsuit shall be borne by the Plaintiff.

1. We examine, ex officio, whether the instant lawsuit is lawful or not, ex officio, as to the determination on the legitimacy of the instant lawsuit.

When a performance suit is pending, the defendant can contest that there is no obligation against the plaintiff by seeking a ruling of dismissal of the claim in the lawsuit, so there is no benefit to seek confirmation that there is no obligation against the plaintiff separately.

(2) Article 271 of the Civil Procedure Act provides that the defendant may withdraw the counterclaim without the plaintiff's consent when the principal lawsuit has been withdrawn. Accordingly, if the plaintiff withdraws the principal lawsuit on the ground that the counterclaim was filed, the defendant unilaterally withdraws the counterclaim and thus the situation in which the plaintiff could not obtain res judicata that the plaintiff initially sought may occur. In light of the fact that the principal lawsuit lawfully raised upon meeting the requirements for the lawsuit does not constitute an unlawful act again due to the defect in the requirements for the lawsuit due to the counterclaim brought by the other party, and that if the plaintiff seeks confirmation on the existence of the non-existence of the damage liability against the defendant as the principal lawsuit, the defendant filed a counterclaim seeking the performance of the damage liability thereafter.

Even if such circumstance alone, it cannot be deemed that the principal lawsuit is unlawful due to the extinguishment of the benefit of confirmation on the principal claim.

(See Supreme Court Decision 2010Da2428, 2435 Decided July 15, 2010. However, in a case where the Defendant, after filing a lawsuit for confirmation of existence of an obligation, files a separate lawsuit, and the Defendant claims the discharge of the obligation, the Plaintiff, even if the Defendant withdraws the separate lawsuit, may seek a judgment of dismissal of the claim, arguing that the Defendant did not have a claim against the Plaintiff (where the Plaintiff has responded to the separate lawsuit pursuant to Article 266(2) of the Civil Procedure Act, the Defendant may withdraw the said performance lawsuit only with the Plaintiff’s consent).