소송상 상계항변에 관하여는 종래 형성권의 소송상 행사와 함께 그 법적 성질에 대한 학설의 대립이 존재하여 왔다. 사법행위설, 소송행위설, 양성설, 신사법행위설 등이 그것이다. 그러나 상계권을 제외한 형성권의 소송상 행사에 대하여는 소송상 항변에 사법상의 형성권 행사의 의사표시와 공격방어방법으로서 그 의사표시의 결과에 대한 진술인 소송행위가 병존하고 있다는 점에 관하여 아무런 견해의 대립이 없었다. 위 학설의 대립은 소송상 상계의 경우 일반적인 형성권의 소송상 행사와 마찬가지로 사법행위와 소송행위가 병존한다고 보는 견해에 따른다면 소의 취하, 각하 또는 실기한 방어방법으로서 항변이 각하되는 경우 등에 있어서도 상계항변에 대한 판단을 받지 못한 채 반대채권이 소멸하는 매우 불합리한 결과를 야기할 수 있다는 이유로 이러한 문제점을 극복하기 위하여 제시된 견해들이었다. 본 대법원판결은 소송상 상계항변이 제출된 후 당해 소송이 조정성립에 의하여 종료된 사안에서 소송상 상계항변의 실체법적 효과가 잔존하지 않음을 밝힌 것이다. 그런데 본 대법원판결은 결론에 있어서는 타당하다고 할 수 있으나, 소송상 상계항변이 예비적 항변이라는 이유로 소구채권의 존재에 관한 법원의 실질적인 판단이 없는 때에는 상계의 의사표시의 효과가 발생하지 않는다고 판시함으로써, 그 이론적 근거를 밝히지 않은 아쉬움이 있다. 이 판결을 계기로 소송상 상계항변이 법적 성질에 관한 종래의 견해들을 살펴보았는바, 소송상 상계항변에 사법행위와 소송행위의 병존을 부인할 수 없고, 상계항변은 예비적 항변으로서의 성격과는 무관하게 무조건의 주장으로서, 상계의 의사표시의 효력은 특정한 상계시에 발생한다고 보아야 한다. 나아가 그 실체법적 효과는 해제조건설에 따라 상계항변이 소송상 참작되지 않는 해제조건이 성취되는 때에 소멸한다고 파악하는 것이 타당하다.

In 2007, the Criminal Procedure Act has been changed into actually new law reflecting the social demands to protect the rights of defendants and suspects in the criminal procedure. The Criminal Procedure Act was revised in 2011, adding the relevance as a requirement of seizure and specifying the range and method of seizure or search on digital evidence. And it supplemented the method of proving the authenticity of digital evidence with some amendments in 2016. It can be said that it has continued to influence the Supreme Court precedent and the precedent also influenced legislation and investigation practice and led to change. This article examines the trends of major cases in the proceedings and evidence law since 2007. The Supreme Court’s cases on investigation procedures and evidence law have consistently emphasized the due process principles of the Constitution and the Criminal Procedure Law, and apply strict standards for existing practices throughout the investigation process including voluntary company, arrest, interrogation, and occasionally have suggested standards and directions of practice from the perspective of judicial control. In particular, in 2007, the Supreme Court ruled that the exclusionary rule of illegally obtained evidence was applied to use of material evidence and the evidence that was illegally collected by the investigating agency in violation of the due process could not be used as evidence of guilt in principle. In the exceptional case that the procedural violation is not equivalent to the violation of the substantive contents of the due process, and the exclusion of the evidence is against the harmonization of the due process and substantive truth in the Constitution and the Criminal Procedure Law, the evidence can be used. Thereafter, the Supreme Court has elaborated the criteria and exceptional jurisprudence on the illegally obtained evidence through various precedents. Since 2007, there have been important precedents related to the seizure of digital evidence, the authenticity and exceptional application of hearsay rule on digital evidence, and specific precedents on the interpretation and standards of exceptional application of hearsay rule of the revised Criminal Procedure Act, which were also the starting point of a new discussion. And this article suggests that, for right judicial justice, the two axes of the due process principle and the request for the discovery of the substantive truth should be mutually realized in harmony rather than abandoning any one.

Criminal procedure holds the discovery of substantive truth as its highest value. However, this fact-finding function cannot be the sole aim of criminal procedure to be attained at all costs. Rather, it is constrained by the principles of due process and a timely trial. Therefore, although the Criminal Code provides for the crime of perjury which deters witnesses from hindering a fair trial with false testimony, the Criminal Procedure Code partially concedes the fact-finding function of criminal procedure by providing for the witness’s right to refuse testimony as a function of due process.This right to refuse testimony is enforced by the obligation to inform the witness on the existence of this right. The question is, if the judge questions a witness in violation of the right to refuse testimony and the obligation to inform, and the witness makes a false statement under oath, can the witness be punished for perjury? This is a question of weighing the values of substantive truth and the principle of due process when they are in contradiction, as due process is the source of the right to refuse testimony and, in certain circumstances, constitutes a limit on the ideal of substantive fact-finding.The decisions in this study take the position that the standard for finding a witness guilty on perjury should be whether there has been an actual hindrance to exercise the right to refuse testimony due to the failure to inform. In this sense, the cases give more weight to the due process considerations of witness examination than previous Korean Supreme Court cases. However, the studied cases are incorrect in limiting the affirmative defense to perjury to those cases where the failure to inform resulted in an actual hindrance to exercise the right. The witness is an individual who bears the obligation to appear at court even though it is not the witness’s own trial, swear a legally binding oath, and testify, all in the interest of substantive fact-finding. The Criminal Procedure Code obligates these witnesses to give testimony, but also gives them the right to refuse testimony where the witness may incriminate himself or herself or close family members. The obligation to inform the witness of this right forms a procedural safeguard to enforce the right. Therefore, the presiding judge’s failure to inform the witness of the existence of the right is a violation of due process and the testimony is given illegally, meaning the witness should not be found guilty of perjury even if the testimony was false.The obligation to inform the witness of the right to refuse testimony exists to guarantee the right to refuse testimony by reminding the witness of the right, thereby giving the witness the ample opportunity to reached an informed decision on whether to stay silent or testify. Therefore, the obligation to inform (Article 160 of the Criminal Procedure Code) guarantees the exercise of this right even when the witness does not know he or she has this right, or is ignorant of how to exercise the right. If the presiding judge violates this regulation and compels the witness to testify without informing the witness that the witness has the right not to testify, such an act on the judge’s part is far more than a minor infraction that has no effect on the legal existence of the crime of perjury. In the cases where the court has failed to inform the holder of the right to refuse testimony, there is no expectation that the witness in question will not commit perjury. It is worth noting that the newly amended Criminal Procedure Code now provides for the exclusion of illegal evidence, and due process is increasingly important at trial as well as during the investigative phase. Therefore, a failure to adhere to laws protecting the witness, especially the failure to inform the witness of a right to refuse testimony should be a full defense to the crime of perjury.