In this blog post, we will examine how criminal procedure law ensures the legality and reliability of evidence through the principle of trial by evidence and the principle of free evaluation of evidence.
Criminal procedure law stipulates that criminal facts must be established by evidence, and the establishment of criminal facts must reach a level of proof beyond a reasonable doubt. This is referred to as the principle of trial by evidence. This means that arbitrary factual determinations by judges are not permitted, and it serves as a prerequisite for ensuring fair and objective criminal trials. Therefore, evidence occupies a central position within the criminal procedure law system. Criminal procedure law distinguishes between the admissibility and probative value of evidence.
First, admissibility refers to the legal qualification of evidence to be used as a means of proof. Admissible evidence can be used as a primary source of factual findings in court and can serve as the basis for a guilty verdict. In principle, inadmissible evidence cannot be used as a source of factual findings.
The requirements for evidentiary admissibility are prescribed by law. The Criminal Procedure Act codifies the conditions under which evidence must be excluded into three principles: the exclusion of illegally obtained evidence, the exclusion of confessions, and the hearsay rule. The common purpose of these principles is to protect the rights of suspects and defendants and ensure a fair trial.
The exclusionary rule for illegally obtained evidence is a principle that denies the admissibility of evidence collected without following proper legal procedures, with the aim of preventing criminal justice authorities from obtaining evidence through unlawful means. Derivative evidence, or secondary evidence, obtained based on facts learned through illegally obtained evidence is also excluded under the exclusionary rule for illegally obtained evidence. This is known as the “fruit of the poisonous tree” doctrine, which compares unlawfully obtained primary evidence to a poisoned tree, and secondary evidence derived from it to the poisoned fruit of that tree. For example, if a statement is obtained through an unlawful arrest without a warrant, not only is the evidentiary value of the statement itself denied, but also the evidentiary value of any physical evidence discovered with the help of that statement. However, if it is determined that the causal relationship between the illegally obtained primary evidence and the secondary evidence has been diluted or severed, the admissibility of the secondary evidence may be recognized. The exclusion of confessions is a principle that denies the admissibility of a confession obtained by investigative authorities or courts in a manner that restricts the voluntariness of the confession.
A confession is an important piece of evidence, but if investigative methods rely solely on obtaining a confession, there is a significant risk of human rights violations, and it may sometimes become difficult to uncover the truth. Therefore, the exclusionary rule on confessions recognizes the admissibility of a confession only if it was made voluntarily by the confessor without physical or mental coercion, thereby prohibiting the coercion of confessions.
The hearsay rule is the principle that hearsay evidence is inadmissible. Hearsay evidence refers to statements made by a person who experienced the matter, such as the defendant or a witness, that were not made directly in court but were indirectly conveyed by another person. Such hearsay evidence includes oral hearsay statements and documentary hearsay evidence. The grounds for the exclusionary rule include the risk of editing or manipulation by the person conveying the statement, the defendant’s inability to cross-examine the witness in court regarding the statement, and the inability of the judge to directly question the declarant in court and obtain accurate linguistic information. However, if the defendant agrees that the expert evidence may be used as evidence, its admissibility is recognized, and this is referred to as “evidentiary agreement.”
On the other hand, probative value differs from admissibility and refers to the extent to which evidence contributes to the determination of facts, i.e., the credibility of evidence as its substantive value. The evaluation of probative value involves assessing the degree of difference in the value of evidence, whereas the evaluation of admissibility merely determines whether evidence is admissible or not.
The fact that evidence has evidentiary capacity does not mean that it has probative value, and the fact that evidence has probative value does not mean that it has evidentiary capacity. The evaluation of probative value is left to the free judgment of the judge, and this principle is called the principle of free evaluation of evidence. When evidence with evidentiary capacity is submitted, the judgment on its evidentiary value is left to the free judgment of the judge. At this time, the judge’s judgment must be based on reasonable grounds, and a mere arbitrary judgment is not justified.
Under the principle of free evaluation of evidence, the judge may freely select evidence and, in cases of conflicting evidence, the decision on which evidence to believe is left to the judge’s discretion. Even if a witness’s testimony lacks credibility, the judge may select and believe a portion of the testimony.
The importance of evidence in the criminal procedure system cannot be overstated. In criminal trials, evidence is not merely a reference material but a decisive element forming the basis of the judgment. All criminal facts must be proven through evidence, and the judge is tasked with determining whether such evidence is legally admissible and how reliable it is. Therefore, in the criminal procedure system, procedures to thoroughly verify and ensure the legality and reliability of evidence are indispensable.
Additionally, protecting the human rights of suspects or defendants during the evidence collection process is crucial. If evidence is not collected lawfully, it must be excluded from the courtroom, serving as a means to ensure procedural justice necessary for the realization of justice. Judges must adhere to these principles while conducting fair trials, thereby maintaining the authority and trust in the law.
Ultimately, evidence in criminal procedure law is not merely important as a legal element but also plays a central role in ensuring social justice and protecting human rights. The importance of evidence is directly linked to the fairness of trials, contributing to the clarification of the truth of crimes and the maintenance of social trust. In this context, the provisions and principles of criminal procedure law regarding evidence serve as important guidelines for ensuring the fairness of legal procedures and assisting judges in making correct decisions.
