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

First, the defendants' grounds of appeal are examined.

1. Medical practice is an area requiring highly specialized knowledge, and it is very difficult for a general person, not an expert, to clarify whether he/she has breached his/her duty of care in the medical process or whether there exists causation between the violation of his/her duty of care and the occurrence of damage. Therefore, it is also possible to presume that the symptoms occur to a patient during the surgery by proving indirect facts that it is difficult to see that there are any other causes than medical malpractice. However, even in such a case, it is not permissible to presume that the symptoms occur due to medical negligence by proving indirect facts concerning the occurrence of the symptoms. However, even in such a case, it is not permissible to estimate the causal relationship between the doctor's negligence and the result by presumption of the causal relationship with the doctor's negligence, with the circumstances where the probability to presume the occurrence of the symptoms is not guaranteed.

(see, e.g., Supreme Court Decision 2010Da96010, 96027, Jun. 27, 2013). Meanwhile, in providing medical treatment, a doctor has a considerable discretion in choosing the methods of medical treatment deemed appropriate according to the patient’s situation, the level of medical care at the time, and his/her knowledge and experience. As long as it does not deviate from the reasonable scope, either one of them is just and the other is not deemed as negligence.

(See Supreme Court Decision 2005Da5867 Decided May 31, 2007, etc.). In addition, in a case where a subsequent disability is caused by medical practice, if the subsequent disability is the best possible measure at the medical level at the time of the pertinent medical practice, or if it is deemed that the subsequent disability could be caused by a merger of the pertinent medical practice process, or by a merger thereof could be caused secondaryly, the content, procedure, and certificate of merger.