Admissibility of Written record of Interrogation as Impeachment Evidence

In this paper, we addressed the issue of whether it is possible to submit a written record of suspect's interrogation, which cannot be used as substantive evidence in court due to the defendant's denial of its contents, as impeachment evidence for proving guilt. While previous Supreme Court precedents have taken an affirmative stance on this matter, there have been dissenting academic opinions and lower court decisions against it. In addition, with the practical importance of this issue increasing after the amendment of the Criminal Procedure Act in 2020, the situation has changed. Although the previous Supreme Court precedents are generally valid, they have failed to sufficiently consider the risk that the fact-finding entity may have limited ability in utilizing such evidence only as impeachment evidence when it has potential risk to be used as substantive evidence. Therefore, this paper presents an interpretative approach that restricts the conditions for using a suspect's statement as impeachment evidence compared to the previous approach. First, impeachment should be limited to specific statements made by the defendant during the interrogation process. Second, the prosecutor should have made reasonable efforts to submit the defendant's statement as substantive evidence. Third, the lawfulness of the suspect's statement and the voluntariness of the confession should be recognized. Fourth, the accuracy of the statement during the writing process should be ensured.