The judgment below is reversed and the case is remanded to Seoul High Court.

The grounds of appeal are examined (to the extent of supplement in case of supplemental appellate briefs not timely filed).

1. As to the defendant's second ground for appeal

A. Article 760(3) of the Civil Act considers an aided person to be a joint tortfeasor and imposes joint tort liability on the aided person.

Assistance refers to all direct and indirect acts that facilitate tort. Aiding and abetting by negligence is possible in the area of civil law in which negligence is the same as that of an intentional act, in principle, for the purpose of compensating for damages. In this case, the content of negligence refers to a violation of the duty of care on the premise that there is a duty of care not to assist a tort.

However, in order to impose joint tort liability for aiding and abetting another person's tort by negligence, proximate causal relation should be acknowledged between aiding and abetting and causing damage to the victim's tort. In determining proximate causal relation, the reasonable causal relation should be determined by comprehensively taking into account the probability of predictability of the situation that facilitates the relevant tort by negligence, as well as the impact of the negligent act on the occurrence of damage, degree of contribution to the formation of trust of the victim, and degree of contribution to the formation of trust of the victim, and whether the victim

(see, e.g., Supreme Court Decision 2013Da91597, Mar. 27, 2014). Therefore, in a case where an account was opened with the use of a third party’s name, it cannot be said that a financial institution should always be liable for damages equivalent to the amount deposited and withdrawn through the original account solely on the ground that the financial institution did not go through the identification procedure, etc. in the process. In order to recognize the liability for damages, a financial institution’s breach of its duty of care and an