Criteria for Illegally Collected Evidence, Shaped by Case Law and Difficult to Predict

It is being pointed out in investigative agencies and the legal community that the standards for determining illegally obtained evidence have been formed through court precedents rather than statutory provisions, making predictability low. The Criminal Procedure Act stipulates that evidence obtained without lawful procedures should not be admitted, but in practice, the legality of searches and seizures and the collection of electronic information has varied depending on court rulings in each case. In some cases, methods accepted at the investigation stage were later judged illegal at the trial stage. Recently, the Supreme Court ruled that even statements derived from illegally obtained evidence must be excluded, taking a stricter view of the scope of illegally obtained evidence. Inside and outside the prosecution, there is a view that such changes are making investigative standards more complicated.