민사소송에서 공동소송인의 증인적격 = Can a co-plaintiff or co-defendent be a witness?

다국어 초록 (Multilingual Abstract)

It is not uncommon in practice for a co-plaintiff or co-defendent to be examined as a witness regarding the content related to their own claim. So far, issues concerning witness examination of a party have mainly been discussed in criminal proceedings, particularly regarding the admissibility of a co-defendant as a witness. Consequently, in civil trials, without special consideration, the arguments of co-plaintiffs or co-defendents may be separated, and witness examinations may be conducted separately. However, it cannot be readily acknowledged that separating arguments to examine related co-plaintiffs or co-defendents as witnesses falls within the discretion of the court's argument separation.
Of course, if a co-plaintiff or co-defendent attends the witness examination voluntarily and testifies, and if the opposing party does not object to it, according to Article 151 of the Civil Procedure Act, the right to object is forfeited, and the evidentiary value of the witness examination results may be recognized. However, the issue of sanctioning for perjury or fines due to the violation of the obligation as a witness by a co-plaintiff or co-defendent is a separate matter. Even if argument separation is within the court's discretion, it is difficult to justify sanctions solely on the grounds that the co-plaintiff or co-defendent violated the duty as a witness after separating arguments solely for witness examination and adopting the co-plaintiff or co-defendent as a witness, as there is no necessity for argument separation or evidence gathering. Instead of examining a co-plaintiff or co-defendant as a witness, there is another type of evidence to consider in examining a co-party, which may offer even greater advantages to the party seeking evidence under Article 369 of the Civil Procedure Act.
Practical improvements in the court's proceedings are expected through the comparison and analysis of the differences between the duties of a witness and those of a party as outlined in this text, along with the introduction of foreign discussions on the limits of argument separation.