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.

The criminal procedure commonly provide for the joinder of defendants, whereby two or more persons may together be prosecuted in a single trial. Assume a case in which defendants A and B have been lawfully joined for trial, but at that trial the prosecution intends to offer against A a confession by him stating, in effect, that he and B committed the crime. That right of an accused in a criminal case to confront the witnesses against him would be violated if A, by his confession, was a witness against B but could not be cross-examined. So to speak, where the powerfully incriminating judicial statements of a codefendant, who stands accused sideby- side with the defendant, are deliberately spread before the judge in a joint trial. In fact, it seems to me that “interlocking” bears a positively inverse relationship to devastation. A codefendant' confession will be relatively harmless if the incriminating story it tells is different from that which the defendant himself is alleged to have told, but enormously damaging if it confirms, in all essential respects, the defendant' alleged confession. It might be otherwise if the defendant were standing by his confession, in which case it could be said that the codefendant' confession does no more than support the defendant' very own case as corroborating evidence. But it might be otherwise if the defendant denies about his confession, in which case it could be said that the codefendant' confession is required as corroborating evidence that supports the defendant' very own case.