공판정 또는 그 외에서 한 공범자의 자백이 다른 공범자인 피고인의 공소사실과 관련하여 증거능력을 가질 수 있는가, 증거능력을 갖는다면 그 요건은 무엇인가 하는 문제, 즉 "공범자의 자백"의 증거능력 및 증명력의 문제는 이론적 또는 실무적으로 중요한 의미를 갖는다. 그리고 공범관계에 있는 공동피고인의 자백을 다른 공범자인 피고인에 대한 유죄증거로 사용할 수 있는가에 관한 논의의 핵심은, 증거법의 기본원칙인 직접심리주의와 전문증거법칙 그리고 자유심증주의와 자백배제 및 자백보강법칙간의 관계설정에 있다. 따라서 공동피고인이 공범자인 경우에는 그 진술의 증거능력을 인정함에 있어서는 이해관계의 특수성에 기한 위험성을 고려하여 보다 신중해야 할 것으로 생각된다. 그렇기 때문에 증거능력과 관련해서는 공판정의 진술보다는 공판정외의 진술의 증거능력을 인정함에 보다 엄격한 제한을 가하는 것이 타당하다.

In 1983, Supreme Court ruled that policemen could not testify to the defendant's confess when the defendant objected. The Court reasoned that since the Code of Criminal Procedure denied the admissibility of the documents which was made by the police and contained the defendant's confess when the defendant object, the policeman was not allowed to testify to that effect, either. The Code of Criminal Procedure, however, does not explicitly prohibit the use of such testimony. As for the document which contains the confess of the defendant, it is extremely difficult to contest. Because the defendant cannot cross-exam the policeman who interrogated the defendant or the defendant himself. But as for the testimony, the reliability can be guaranteed by the cross-examination. In addition, such testimony often includes first-handed, accurate information and cannot be obtained otherwise. This study is an attempt to illustrate such an occasion. In this case which was ruled in 2005, Supreme Court once again denied the admissibility of the interrogator's testimony. However there are some special elements to be considered. Here, the policeman met the defendant near the crime scene just after he had committed homicide; the setting was not interrogatory; the defendant freely admitted that he had killed the victim. If he had met a civilian, he would have told the same story. In situation like this, there is no danger of misconception, manipulation, or memory lapse. This case clearly shows that under certain circumstance it is necessary, sometimes desirable to admit interrogators' testimony. In conclusion, the admissibility of the policeman's testimony should not be decided uniformly. Rather, it should be decided case by case in the light of reliability.