[Invest&Law] Stricter Standards for 'Illegally Collected Evidence'

In recent trials, evidence collected by investigative agencies has been repeatedly excluded on the grounds of illegality. Especially as mobile phones have emerged as key evidence, courts are once again clarifying the legal principles regarding the Exclusionary Rule on Illegally Obtained Evidence (Wi-su-jeung).

"Evidence collected without following lawful procedures cannot be used as evidence." Article 308-2 of the Criminal Procedure Act explicitly states Wi-su-jeung, a core principle that prevents illegal searches and seizures by investigative agencies. Since this principle was codified in the Criminal Procedure Act in June 2007, courts have controlled indiscriminate searches and seizures by investigative agencies. In particular, with the spread of smartphones and the increase in electronic information searches, stricter legal doctrines have been established.

On the 8th, Song Young-gil, leader of the Sonamu Party, who was sentenced to two years in prison and detained in court on charges including violation of the Political Parties Act, Political Funds Act, and bribery, was acquitted on charges related to the "Democratic Party Convention Money Envelope" case due to Wi-su-jeung. The Criminal Division 21 of the Seoul Central District Court (Presiding Judge Heo Kyung-moo) ruled that the recorded phone calls from the mobile phone of former Democratic Party Deputy Secretary-General Lee Jeong-geun, who was under investigation for a bribery solicitation case, were "illegally collected evidence unrelated to the bribery solicitation case," and stated, "Despite the need to ascertain the substantive truth, the evidence must be excluded to suppress illegal searches and seizures by investigative agencies and prevent recurrence."

Strict Judgment on Voluntariness of Submission

The court particularly scrutinized the authenticity of the "voluntary submission" made while in custody. Lee repeatedly lied about the whereabouts of his mobile phone from August to October 2022 before submitting it belatedly, stating about his state of mind at the time, "I was so scared of being under custody investigation that I thought cooperating with the prosecution would help me get out of here." The court recognized the possibility that the prosecution's investigative environment acted as pressure. Furthermore, Lee maintained his claim that he had discarded the mobile phone until 10 p.m. on October 7, 2022, after the video recording of the suspect interrogation ended, but suddenly changed his position about 30 minutes later, with unclear circumstances.

The court found that Lee submitted the information on the mobile phone without clearly knowing the scope of the data. He consistently testified that he submitted the files recorded by the automatic recording device without knowing much about them, and the actual amount of extracted electronic information reached hundreds of thousands of items, indicating that Lee did not clearly understand or express his intention regarding the scope of submission.

The court stated, "Although the prosecutor repeatedly recorded in the minutes the questioning confirming the scope of voluntary submission, the questions were abstract and comprehensive, and only short answers were given, so such questioning alone cannot replace a search warrant," and added, "The problematic recorded phone files are evidence that would punish Lee as a co-conspirator in the money envelope case, but there is no material to suggest that he knowingly expressed his intention to submit all incriminating evidence that would punish himself to the investigative agency without knowing what he was submitting."

On the other hand, after the verdict, the prosecution argued, "Lee voluntarily expressed his intention to submit the mobile phone during the investigation with the assistance of counsel, and repeatedly clarified his intention and scope of voluntary submission during the investigation and in court." They further claimed, "In related cases where the same issue was raised, judgments were repeatedly made that the mobile phone was voluntarily submitted, and there was even a Supreme Court final ruling based on the legality of the mobile phone for some co-conspirators."

‘Wi-su-jeung’ Emerging as an Increasingly Important Issue

Wi-su-jeung is a contentious issue not only in the Song Young-gil case but also in several major cases. Kim Tae-han, former CEO of Samsung Biologics, who was indicted on charges of instructing evidence destruction during the listing process, was acquitted in the first trial on February 1, 2024. The Seoul Central District Court ruled that the evidence duplicated from related servers lacked evidentiary value due to failure to follow proper procedures.

In April 2024, the Supreme Court ruled that investigative agencies' act of storing unrelated information on the prosecution’s server during a mobile phone search and seizure and using it for separate investigations without a warrant constituted illegally obtained evidence. In a case involving a prosecutorial investigation clerk, investigative agencies explored, duplicated, and printed recorded files found on mobile phones related to other cases without a warrant for three months and used them as evidence. The Supreme Court found these actions violated the warrant principle and due process, denying the evidentiary value of both the evidence and secondary evidence collected through it.

In a case where the Republic of Korea Army’s Defense Security Command retained past search and seizure materials without disposal and initiated separate internal investigations based on them, the Supreme Court ruled in June 2023 that "investigative agencies must delete or dispose of electronic information unrelated to the alleged facts after completing the seizure," and evidence collected in violation of this cannot be used in court.

In the legal community, as courts continue to reaffirm the legal principles of Wi-su-jeung through successive rulings, opinions are emerging that investigative agencies need to change their investigative methods accordingly.

Professor Noh Su-hwan of Sungkyunkwan University Law School emphasized, "The key issue in mobile phone searches and seizures is that the discovered evidence must be 'incidentally discovered evidence.' If it is not incidentally discovered, even if a warrant is obtained, it can be illegal evidence. Investigative agencies must change their investigative methods in line with the strengthening legal trends and deepen their consideration of compliance with due process."

Attorney Lee Sang-cheol of the law firm Taepyungyang said, "Procedural justice must not be compromised under the pretext of ascertaining substantive truth," adding, "The importance of due process will be further emphasized in the future, and since the judiciary’s role is to control and regulate arbitrary investigations by investigative agencies through the Wi-su-jeung principle, investigative agencies also need to consider how to change their investigative methods going forward."

Reporter An Jae-myung, Legal Newspaper