In this blog post, we will examine the difference between admissibility and probative value, focusing on the Criminal Procedure Act, and explore the roles each plays in criminal trials.
Criminal Procedure Law stipulates that criminal facts must be established by evidence, and that the establishment of such facts must reach a standard of proof beyond a reasonable doubt; this is known 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 framework of Criminal Procedure Law. 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 basis for proof. Evidence that is admissible can be used in court as a basis for determining key facts, and a guilty verdict can be rendered based on it. Evidence that is not admissible cannot, in principle, be used as a basis for determining facts. The requirements for admissibility are prescribed by law. The Criminal Procedure Act codifies the conditions under which admissibility must be excluded into three principles: the exclusionary rule for illegally obtained evidence, the exclusionary rule for confessions, and the hearsay rule. The common purpose of these principles is to guarantee the rights of suspects and defendants and to ensure a fair trial.
The exclusionary rule denies the admissibility of evidence collected without following lawful procedures, with the aim of deterring unlawful evidence collection by criminal justice agencies. The admissibility of derivative evidence—that is, secondary evidence—obtained based on facts learned through unlawfully collected evidence is also excluded under the exclusionary rule. This is known as the “fruit of the poisonous tree” doctrine: if the unlawfully collected primary evidence is likened to a tree contaminated with poison, the secondary evidence derived from it is considered the poisonous fruit that grows on that tree. For example, if a statement is obtained during an unlawful arrest without a warrant, not only is the evidentiary value of that statement denied, but so is the evidentiary value of any physical evidence discovered with the aid of that statement. However, if it is determined that the causal link between the unlawfully obtained primary evidence and the secondary evidence has been diluted or severed, the admissibility of the secondary evidence may be recognized.
The exclusionary rule for confessions is a principle that denies the admissibility of a statement when investigative authorities or courts obtain a confession from a declarant in a manner that restricts its voluntariness. Although confessions are important evidence, if investigative methods rely solely on obtaining confessions, there is a significant risk of human rights violations, and it may sometimes become difficult to uncover the truth. Accordingly, the exclusionary rule prohibits the coercion of confessions by recognizing as admissible only those confessions made voluntarily by the subject of the confession, without physical or mental pressure.
The hearsay rule is the principle that hearsay evidence lacks probative value. Hearsay evidence refers to testimonial evidence—statements made orally by a defendant, witness, or other person who experienced the events—that is not presented directly in court but is conveyed indirectly by another person. Such hearsay evidence includes oral hearsay statements and documentary hearsay. The grounds for the hearsay rule include the risk of editing or manipulation by the person conveying the testimony, the fact that the defendant cannot cross-examine the witness in court regarding the hearsay evidence, and the fact that the judge cannot obtain accurate verbal information because they cannot directly question the declarant and hear their response in court. However, even if evidence is hearsay, its admissibility is recognized if the defendant agrees to its use as evidence; this is referred to as “consent to evidence.”
Meanwhile, probative value, unlike admissibility, refers to the degree to which evidence can contribute to the determination of facts—that is, the credibility of the evidence as its substantive value. The evaluation of probative value involves assessing the degree of the evidence’s value, which differs from the evaluation of admissibility, which merely determines whether evidence is admissible or not. Admissibility does not imply probative value, nor does probative value imply admissibility.
The assessment of probative value is left to the judge’s discretion; this principle is known as the principle of free evaluation of evidence. Once admissible evidence is submitted, the judgment regarding its evidentiary value is based on the judge’s discretion. In this case, the judge’s judgment must be grounded in reasonable grounds, and mere arbitrary judgment is not justified. Under the principle of free evaluation of evidence, the judge is free to select and weigh evidence, and in cases where there is conflicting evidence, the decision as to which evidence to accept is left to the judge’s discretion. Even if a witness’s testimony lacks credibility, the judge may select and accept certain parts of it.
The Criminal Procedure Act establishes strict rules regarding evidence, aiming to prevent arbitrary judgments by the judge. This is an essential element in ensuring the fairness and objectivity of criminal trials. Therefore, the principle of trial by evidence is one of the key principles underpinning the rule of law, contributing to the protection of the defendant’s rights and the maintenance of public trust in the criminal justice system. Within this framework, the process of strictly distinguishing between the admissibility and probative value of evidence, and evaluating the substantive value of each piece of evidence, plays a crucial role in enhancing the quality of criminal trials.
