The Warrant Requirement in Search and Seizure and the Limits of Admissibility: Voluntary Production, Relevance, and Defence Counsel's Documents

Question

Even where an investigative authority has recorded that it received an object such as a mobile phone by voluntary submission, if it is doubtful whether that delivery was truly voluntary, who must resolve that doubt, and by what means. Under the framework of Article 218 and Article 308 of the Criminal Procedure Act, voluntary submission is an exception permitting seizure without a warrant, and therefore the direction and the standard of the proof surrounding the fact that the requirements of that exception are satisfied is at issue.

The electronic information contained in a voluntarily submitted smartphone, unlike the object itself, holds vast amounts of private information, and the extent to which viewing and extraction is permitted is at the center of the dispute. Article 106, Article 218, and Article 219 of the Criminal Procedure Act and Article 62 and Article 109 of the Regulations on Criminal Procedure take relevance as their standard, but depending on whether that relevance is confined to direct evidence or extends to indirect evidence or circumstantial evidence, the scope of the investigation and the breadth of the right of defense differ greatly.

Legal advisory documents exchanged between the suspect and counsel are the core material of the right of defense, and whether they may be subject to seizure is a separate issue. Between the right to assistance of counsel guaranteed by Article 12, paragraphs (4) and (5) of the Constitution and Article 34 of the Criminal Procedure Act, and the seizure power of the investigative authorities, which side should be given priority, and at what line an exception may be recognized, is at issue.

Material to check

Begin with the documents recording how the voluntary production came about. The voluntary production confirmation form, any audio or video recording of the production, the record of the producer's statements, the statements of any person present at the time, the time and place of production, and the manner in which the investigator made the request and how the producer responded should each be checked against one another. In particular, examine whether the record shows how the producer was told what voluntary production means and that the item might not be returned.

The procedural records of seizure and inspection should be reviewed together. Check whether the following are inconsistent across the materials: the list of seized items, the search and seizure warrant and the scope stated in its attachment, the manner in which the investigative agency kept the item after receiving it, the time of unsealing and inspection, the persons who took part and their capacity, and the consistency of the documents prepared at the scene of seizure. In determining admissibility under Articles 307 and 308 of the Criminal Procedure Act, these procedural records are the starting point for the facts.

The materials showing the scope of extraction of electronic information are central. Review the digital forensic report, the list of extracted files and their creation times, the items inspected within the inspection warrant or the scope of the voluntary production, any traces of deletion or alteration, and the working records showing how the investigator located information connected to the specific suspected offence. Also check whether these records state how the standards set out in Articles 62 and 109 of the Rules of Criminal Procedure were applied.

The final category is the procedural materials showing whether documents relating to defence counsel were separated. Look for materials on whether legal-advice documents were identified at the scene of seizure; if so, whether those materials were excluded from the list; whether the suspect or defendant consented to the seizure from defence counsel as the person from whom the items were seized; and whether defence counsel was an accomplice of the suspect or defendant or was involved in the suspect's or defendant's crime or other unlawful act. These materials contain the grounds for deciding whether Article 12(4) and (5) of the Constitution of the Republic of Korea and Articles 34, 112, 149, 199(1) and 219 of the Criminal Procedure Act apply.

Possible readings

On the voluntariness of a voluntary production, one reading holds that the voluntary nature of the production is presumptively established by the written or on-scene record alone, and that the party raising doubt must present specific circumstances. This reading rests on practical efficiency at the investigative scene and respect for what the producer said. The opposing reading holds that, because voluntary production is an exception to the warrant requirement, the prosecutor bears the burden of proving the requirements of the exception, and that once suspicious circumstances emerge, the prosecutor must go as far as proving facts that dispel the doubt. The issue is which reading fits more coherently within the scheme of Articles 218, 308 and 308-2 of the Criminal Procedure Act.

On the relevance that defines the scope of seizure, too, a narrow reading and a broad reading are opposed. The narrow reading holds that only information directly proving the suspected facts that prompted the production may be seized, and that any other information falls outside the scope. The broad reading holds that information usable as indirect or circumstantial evidence revealing the motive and circumstances of the offence, its means and method, and its time and place is also included. Even under the broad reading, however, the information must relate to the suspected facts and have at least the minimum value needed to prove them, which narrows the gap between the two positions.

On the seizure of legal-advice documents, one reading holds that seizure should be permitted without exception where the need to gather evidence is compelling. The opposing reading holds that legal advice between defence counsel and client is the foundation of the right of defence, so that its seizure should in principle be prohibited, and that an exception should be allowed only where there is a compelling public-interest necessity, such as the suspect's consent or counsel's participation as an accomplice, and only upon a strict determination that comprehensively considers all the circumstances. The latter reading carries greater weight because it accords with the purpose of Articles 34 and 219 of the Criminal Procedure Act.

What the decisions held

In Supreme Court 2020Do9431, which concerned the admissibility of a mobile phone obtained by voluntary production and the electronic information on it, the Court drew the line that it is not for the defendant to prove reasonable and specific facts casting doubt on the voluntariness of the production; rather, the prosecutor must prove facts that dispel the doubt as to voluntariness. Because that proof was insufficient in the case, the Court held that the mobile phone and the electronic information must be regarded as illegally obtained evidence without admissibility. Addressing Articles 218 and 308 of the Criminal Procedure Act together with Article 14(1) of the former Act on Special Cases Concerning the Punishment of Sexual Crimes, the Court set out the effect of the procedural violation on admissibility within the framework of Articles 308-2 and 325 of the Criminal Procedure Act.

In Supreme Court 2020Do2550, a case of illegal filming with a smartphone, the Court set standards for the scope of seizure of voluntarily produced electronic information. Proceeding from the premise that information may be seized only if it relates to the suspected criminal facts that prompted the voluntary production and has at least the minimum value needed to prove them, the Court held that information usable as indirect or circumstantial evidence of the motive and circumstances of the offence, its means and method, its time and place, and the like may also be included. It held that a specific and individual nexus may be recognised for indirect or circumstantial evidence found in electronic information of the same type where the offence is suspected to be habitual, or to be part of a series of offences manifesting a sexual preference or tendency, and where direct evidence of the offence is likely to remain in the form of image or video files. It further held that the prosecutor must prove the voluntariness of the production beyond reasonable doubt.

In Supreme Court 2024Mo730, a case in which legal-advice documents of defence counsel for a suspect not in custody were seized, the Court held that the seizure of legal-advice documents and the like concerning a criminal case created between a suspect and defence counsel is liable to infringe the constitutional right to the assistance of counsel and related rights, and therefore must not, in principle, be permitted. It set the standard that exceptions are confined to cases of compelling public-interest necessity, such as where the suspect or defendant has consented to the seizure of legal-advice documents and the like from defence counsel as the person from whom the items were seized, or where defence counsel is an accomplice of the suspect or defendant or was involved in the suspect's or defendant's crime or other unlawful act, and that the determination must be made strictly, considering all the circumstances comprehensively. The Court held that the seizure of the materials in the case did not fall within that exception and was therefore unlawful.

Practical checklist

First, check how, in the course of the production, the investigator informed the producer of the meaning of voluntary production and that the item would not be returned, whether that explanation was oral or written, and whether the record confirms whether anyone was present at the scene. Within the framework of Articles 218 and 308 of the Criminal Procedure Act, the manner and timing of that explanation are the key starting point for assessing voluntariness.

Second, check whether the produced material is information that relates to the suspected facts that prompted the voluntary production and has at least the minimum value needed to prove them, and whether the scope of inspection stayed within that relevance. If information usable as indirect or circumstantial evidence was also handled, confirm whether it concerns the motive and circumstances of the offence, its means and method, or its time and place, and whether there is a specific and individual nexus, and then determine whether relevance is established. The prosecutor must prove beyond reasonable doubt that the production was voluntary.

Third, confirm whether legal-advice documents were identified at the scene of seizure; if so, whether they were separated and excluded from the list; whether the suspect or defendant consented to the seizure from defence counsel as the person from whom the items were seized; whether defence counsel was an accomplice; and what any other compelling public-interest necessity is. Examine the requirements for an exception strictly in light of Article 12(4) and (5) of the Constitution of the Republic of Korea and Articles 34, 112, 149, 199(1) and 219 of the Criminal Procedure Act.

Fourth, set out the effects of any procedural violation. Bearing in mind that, if material whose voluntariness remains in doubt or material beyond the permitted scope was to be used as evidence, its admissibility is in question under Articles 307, 308, 308-2 and 325 of the Criminal Procedure Act, carry out a final check of whether the investigative agency's records were prepared fully enough to dispel the doubt.

Glossary

Voluntary production means that the owner or possessor of an item voluntarily hands it over to an investigative agency; it is one of the exceptions under Article 218 of the Criminal Procedure Act that permit seizure without a warrant. Where it is disputed whether the production was truly voluntary, once suspicious circumstances have emerged the prosecutor must prove facts that dispel the doubt. The mere fact that a written confirmation form was obtained does not always establish voluntariness.

Relevance is the standard that defines the scope of information subject to seizure. Information may be seized only if it relates to the suspected criminal facts that prompted the voluntary production and has at least the minimum value needed to prove them, and this includes information usable as indirect or circumstantial evidence revealing the motive and circumstances of the offence, its means and method, and its time and place. However, where the offence is suspected to be habitual or part of a series of offences driven by a sexual preference, as in illegal filming with a smartphone, strong indirect or circumstantial evidence found in electronic information of the same type may be recognised as having a specific and individual nexus with the suspected criminal facts. The prosecutor, for its part, must prove the voluntariness of the production beyond reasonable doubt.

Legal-advice documents means advice and records created between a suspect and defence counsel concerning a criminal case. In order to protect in substance the right to the assistance of counsel guaranteed by Article 12(4) and (5) of the Constitution of the Republic of Korea, the seizure of such documents must not, in principle, be permitted; an exception is allowed only where there is a compelling public-interest necessity, such as where the suspect or defendant has consented to the seizure from defence counsel as the person from whom the items were seized, or where defence counsel is an accomplice of the suspect or defendant or was involved in the suspect's or defendant's crime or other unlawful act, and only upon a strict determination that comprehensively considers all the circumstances.

Sources and limitations

This brief was prepared solely on the basis of Supreme Court 2020Do9431, Supreme Court 2020Do2550 and Supreme Court 2024Mo730, the provisions of the Criminal Procedure Act, the Rules of Criminal Procedure and the Constitution of the Republic of Korea cited in those decisions, and Article 14(1) of the former Act on Special Cases Concerning the Punishment of Sexual Crimes. The facts of each case are described only to the extent found in those decisions, and no other cases or materials are cited.

This material has been compiled for general research purposes and is not legal advice. Because the outcome of an individual case may vary with the specific facts and evidence, in an actual case the original text of the provisions and the judgments should be checked directly with the assistance of counsel. The full text of the judgments is available from the National Law Information Center.

Points left open

Specific criteria as to how an investigative authority must give notice of the meaning of voluntary submission and the circumstance that the item would not be returned in order for voluntariness to be recognized have not yet been established. Whether a written confirmation form or an oral explanation is to be regarded as sufficient, whether the conclusion changes if the timing and method of the explanation differ, and whether the age or level of knowledge of the person making the submission must be taken into account: Supreme Court Decision 2020Do9431 did not directly answer these. Whether information of the same type contained in ordinary storage media other than smartphones is likewise recognized as having a concrete and individual connection under the same criterion also lies outside the scope of the determination in Supreme Court Decision 2020Do2550.

The question also remains whether legal advisory documents, etc. that were seized upon recognition of a grave public interest need may be used as evidence in a related case. Although Supreme Court Decision 2024Mo730 presented the permissibility of the seizure itself and the criteria for determination, it did not expressly address how exceptionally seized materials will be treated in subsequent evidentiary use. The scope of the effect of consent and the concrete criteria for determining an accomplice relationship also leave room to be refined in future cases.

When to reconsider

This white paper must be reexamined if a new Supreme Court decision is rendered concerning the method of giving notice in voluntary submission procedures or the allocation of the burden of proof, or if Article 218, Article 308, and Article 308-2 of the Criminal Procedure Act are amended. The same measure is needed if amendments are made to the Regulations on Criminal Procedure governing the criteria for determining the relevance of electronic information or digital forensic procedures.

This must also be organized anew if new determinations are made concerning the requirements of consent, the scope of the accomplice relationship, and the permissibility of evidentiary use in connection with the exception to the seizure of counsel's legal advisory documents, or if Article 12, paragraphs (4) and (5) of the Constitution and Article 34, Article 112, Article 149, Article 199, paragraph (1), and Article 219 of the Criminal Procedure Act are amended. In addition, each time trends in case law after 2026-10-15 are confirmed, the reference date and the body text of this white paper are updated.

Statutes referred to

• 형사소송법 제34조, 제106조, 제112조, 제149조, 제199조 제1항, 제218조, 제219조, 제307조, 제308조, 제308조의2, 제325조
• 형사소송규칙 제62조, 제109조
• 헌법 제12조 제4항, 제5항
• 구 성폭력범죄의 처벌 등에 관한 특례법(2018. 12. 18. 법률 제15977호로 개정되기 전의 것) 제14조 제1항

Decisions referred to

• 대법원 2024. 3. 12. 선고 2020도9431 판결 · Decision ledger
• 대법원 2023. 6. 1. 선고 2020도2550 판결 · Decision ledger
• 대법원 2026. 2. 20. 자 2024모730 결정 · Decision ledger

Verification status

The original texts of the relevant provisions and the judgment texts of Supreme Court Decision 2020Do9431, Supreme Court Decision 2020Do2550, and Supreme Court Decision 2024Mo730 were cross-checked on the Korea Law Information Center as of 2026-10-15. This white paper cites only the three decisions addressed herein.