The Exclusionary Rule for Unlawfully Collected Evidence in South Korea

By Juwon Kang, July 12, 2026

The Big Picture

1. The Basis and Principle of the Exclusionary Rule

Article 308-2 of the Criminal Procedure Act expressly codifies the exclusionary rule for unlawfully collected evidence, providing that “evidence collected without following due process cannot be used as evidence” (Criminal Procedure Act, Article 308-2).

This is intended to realize the constitutional ideal of guaranteeing the people’s fundamental human rights by suppressing and preventing the recurrence of unlawful acts in the investigation process, including unlawful seizure and search; and not only evidence collected without following due process but also secondary evidence obtained on its basis cannot, in principle, be used as evidence for a finding of guilt (Supreme Court, July 11, 2019, 2018do20504).

2. Recent Key Judgments

A. Supreme Court, Sept. 25, 2025, 2025do10418 (violation of the Act on the Aggravated Punishment of Specific Crimes (bribery), etc.). A case in which the lawfulness of the seizure and search of electronic information, and the application of the exception to the exclusionary rule, were at issue. The Supreme Court judged that the lower court had not erred in misapprehending the legal principles on the lawfulness of the seizure and search of electronic information and the exception to the exclusionary rule, and dismissed the appeal.

B. Supreme Court, July 16, 2025, 2025do6183 (violation of the Act on the Aggravated Punishment of Specific Crimes (psychotropic drugs)). A case in which the exclusionary rule and the admissibility of secondary evidence were at issue. The Supreme Court found that the lower court’s judgment had not erred in misapprehending the legal principles on the exclusionary rule and the admissibility of secondary evidence, and dismissed the appeal.

C. Supreme Court, July 3, 2025, 2024do12274 (violation of the Local Finance Act). A case in which the application of the exclusionary rule was at issue. The Supreme Court judged that the lower court’s judgment had not erred in misapprehending the legal principles on the exclusionary rule and the like, and dismissed the appeal.

D. Supreme Court, May 15, 2025, 2025do3846 (violation of the Act on the Control of Narcotics, etc. (psychotropic drugs)). A case in which the lawfulness of the arrest, the guarantee of the participation right of the suspect as the person whose property was seized in the seizure-and-search procedure, and the exclusionary rule were at issue in combination. The Supreme Court found no error in the lower court’s judgment on these principles, and dismissed the appeal.

E. Supreme Court, Feb. 12, 2026, 2025do15592 (violation of the Special Measures Act on the Control of Public Health Crimes, etc.). A case in which—together with “sale of pharmaceuticals” under the Pharmaceutical Affairs Act and “unlicensed medical practice” under the Medical Service Act—the exclusionary rule and admissibility were at issue. The Supreme Court judged that the lower court’s judgment had not erred in misapprehending the legal principles on the exclusionary rule, admissibility, and the like, and dismissed all the appeals.

3. The Exception to the Exclusionary Rule — the Core Principle

The core of the exception principle repeatedly confirmed in the above recent judgments is the following standard, established in Supreme Court, July 11, 2019, 2018do20504.

Where the investigative agency’s procedural violation does not amount to an infringement of the substantive content of due process, but rather it is an exceptional case assessed as one in which excluding admissibility would bring about a result contrary to the purport of realizing criminal-justice justice, the court may use that evidence as evidence for a finding of guilt.

Whether this applies must be judged by examining as a whole and comprehensively: (1) the purport of the procedural provision; (2) the content and degree of the violation; (3) the concrete course of the violation and its avoidability; (4) the nature of the right or legal interest to be protected and the degree of its infringement; (5) the relevance to the defendant; (6) the relevance between the procedural violation and the collection of the evidence; and (7) the investigative agency’s perception and intent (Supreme Court, July 11, 2019, 2018do20504).

The same principle applies to secondary evidence, and in this case the judgment centers on whether the causal connection between the procedural violation and the collection of the secondary evidence is diluted or severed (Supreme Court, Mar. 14, 2013, 2010do2094).

4. Whether It Applies in Administrative Litigation

Meanwhile, recent judgments also confirm that the exclusionary rule does not apply in administrative litigation in the same way as in criminal litigation. The court’s consistent position is that the Administrative Litigation Act and the Civil Procedure Act applied mutatis mutandis have no provision on excluding the admissibility of unlawfully collected evidence, and that—criminal litigation and administrative litigation differing in their structure and purpose—the exclusionary rule of criminal litigation cannot be regarded as applying to administrative litigation as it is (Suwon High Court, Oct. 18, 2024, 2023nu14646; Daegu High Court, July 25, 2025, 2024nu12703).

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The Exclusionary-Rule Exception: The “Infringement of the Substantive Content of Due Process” Standard and Its Application

1. Overview of the Legal Structure

Article 308-2 of the Criminal Procedure Act provides that “evidence collected without following due process cannot be used as evidence” (Criminal Procedure Act, Article 308-2). The Supreme Court, however, holds that even unlawfully collected evidence may be used as evidence for a finding of guilt in an exceptional case where (1) the investigative agency’s procedural violation does not amount to an infringement of the substantive content of due process, and (2) it is rather assessed as one in which excluding admissibility would bring about a result contrary to the purport of realizing criminal-justice justice (Supreme Court, Apr. 28, 2022, 2021do17103; Supreme Court, July 11, 2019, 2018do20504).

Whether this exception applies is judged by examining as a whole and comprehensively: (1) the purport of the procedural provision; (2) the content and degree of the violation; (3) the concrete course of the violation and its avoidability; (4) the nature of the right or legal interest to be protected and the degree of its infringement; (5) the relevance to the defendant; (6) the relevance between the procedural violation and the collection of the evidence; and (7) the investigative agency’s perception and intent (Supreme Court, Apr. 28, 2022, 2021do17103).

Moreover, the burden of proving the concrete and special circumstances that would warrant regarding the case as falling within the exception lies with the prosecutor (Supreme Court, Mar. 12, 2009, 2008do763).

Below, how the courts actually apply this standard is examined concretely, divided into cases recognizing the exception and cases denying it.

2. Cases Recognizing the Exception — Where Admissibility Was Recognized

A. Misstatement of the breath-test result (Suwon District Court, Pyeongtaek Branch, Oct. 5, 2023, 2022godan2423)

Facts: An officer measured the defendant’s blood-alcohol concentration at 0.300% but, by mistake, gave notice of it as 0.030%; he then tracked the defendant down and, while re-notifying him, corrected the drunk-driving enforcement-result notice, but did not obtain the defendant’s confirming signature.

The court’s judgment: The court recognized the exception, taking the following circumstances together:

• The officer’s wrong notice was by mistake and not intentional.
• Had the officer entered a false figure, he would be punished for the offense of preparing a false official document.
• The defendant admitted the fact of the re-notification itself and personally signed the intoxicated-driver circumstances-statement report.
• For the defendant to escape criminal punishment owing to a notice mistake caused by error would bring about a result contrary to the purport of realizing criminal-justice justice.

(Suwon District Court, Pyeongtaek Branch, Oct. 5, 2023, 2022godan2423)

B. Non-delivery of the voluntary-submission document and seizure list upon voluntary submission (Busan High Court, Jan. 12, 2023, 2022no382)

Facts: While receiving a mobile phone and SD card by voluntary submission from the defendant, the police did not prepare a voluntary-submission document and did not deliver a seizure list either.

The court’s judgment: While recognizing the procedural violation, the court recognized the exception, citing the following circumstances:

• The defendant submitted them voluntarily at the officer’s request, and the parents raised no objection.
• The officer’s failure to prepare a voluntary-submission form in advance arose from an unexpected situation.
• The police tried to perform the procedures performable on the scene (preparing a confirmation of the removal of the original storage medium, sealing, etc.).
• When evidence of a separate case was found during forensics, they immediately halted the search and obtained a separate warrant.
• The defendant first contested voluntariness and refused to sign only after the suspect interrogation ended.

(Busan High Court, Jan. 12, 2023, 2022no382)

C. Failure to obtain an after-the-fact warrant following an emergency seizure (Busan District Court, July 7, 2023, 2022no3615)

Facts: The police acquired a seized item without meeting the requirements for emergency seizure under Article 216(3) of the Criminal Procedure Act and also failed to obtain an after-the-fact seizure-and-search warrant; but they subsequently obtained and executed a separate advance seizure-and-search warrant.

The court’s judgment: The court recognized the exception, finding that—the seized item being an object whose very possession is prohibited, the defendant had no reasonable ground to demand its return; the defendant, being in custody, was realistically in a state unable to have it returned; and recognizing the lawfulness of the subsequent seizure by a lawful warrant accords with the purport of realizing criminal-justice justice (Busan District Court, July 7, 2023, 2022no3615).

D. Omission of notice of counsel’s participation (Supreme Court, Apr. 24, 2025, 2024do19106)

Facts: The investigative agency omitted notice to counsel of participation when executing a seizure-and-search warrant.

The court’s judgment: The Supreme Court—while pointing out that the lower court had misapprehended the legal principle on counsel’s participation right—found that, taking the concrete circumstances together, the procedural violation did not amount to an infringement of the substantive content of due process, but rather fell within the exceptional case where excluding admissibility would be contrary to the purport of realizing criminal-justice justice, and dismissed the appeal (Supreme Court, Apr. 24, 2025, 2024do19106).

3. Cases Denying the Exception — Where Admissibility Was Excluded

A. Seizure of separate-case electronic information (Supreme Court, Aug. 14, 2025, 2020do10908)

Facts: A military prosecutor of the special investigation unit on the Defense Security Command allegations obtained a seizure-search-verification warrant concerning A’s suspected conspiracy to commit insurrection and the like, seized the mobile phone of the defendant—who was a reference witness—and generated a duplicate; then, while analyzing an Excel file of all the information extracted from it, found KakaoTalk conversation content related to the defendant’s separate-case suspicion of leaking military secrets, and obtained an additional warrant.

The court’s judgment: The Supreme Court denied the exception, holding as follows:

• The series of procedures—generating an Excel file from the mobile-phone duplicate and using it to acquire the KakaoTalk conversation content—amounted to an unlawful seizure contrary to the warrant requirement and the due-process principle.
• The unlawfulness cannot be regarded as cured merely because the seizure was made under the subsequently obtained additional seizure-search-verification warrant.
• The secondary evidence collected on the basis of the KakaoTalk conversation content also cannot be regarded as having its causal connection diluted or severed, and so is all inadmissible.

(Supreme Court, Aug. 14, 2025, 2020do10908)

B. Violation of the breath-test procedure (Seoul Central District Court, May 8, 2024, 2023no2865)

Facts: The investigative agency committed a procedural violation in the breath-test process that infringed the substantive content of the due-process principle guaranteed by the Constitution and the Criminal Procedure Act.

The court’s judgment: The court judged that, the procedural violation amounting to an infringement of the substantive content of the due-process principle, it did not fall within a case where admissibility could exceptionally be recognized. It also emphasized that, because recklessly recognizing the exception risks undermining the principle that unlawfully collected evidence cannot be used as evidence of guilt, the court must bear this in mind (Seoul Central District Court, May 8, 2024, 2023no2865).

C. Warrantless search and secondary evidence (Seoul Southern District Court, Aug. 24, 2023, 2021godan2858)

Facts: The police searched a massage establishment without a warrant and collected evidence.

The court’s judgment: The court found that both the evidence collected in the course of the unlawful search and the secondary evidence obtained on its basis amounted to unlawfully collected evidence, and that the prosecutor had failed to prove the existence of the concrete and special circumstances that would warrant regarding the case as exceptional; it denied admissibility of all of it and acquitted (Seoul Southern District Court, Aug. 24, 2023, 2021godan2858).

D. Non-delivery of the detailed list of electronic information, and analysis of unrelated information (Suwon District Court, Jan. 13, 2025, 2024no2446)

Facts: The investigative agency did not deliver a detailed list of the seized electronic information, and—without informing the defendant that a compressed file within the seized electronic medium would not open properly—merely presented a list of file names and paths at the suspect interrogation.

The court’s judgment: The court assessed this procedural violation as a grave violation of the warrant requirement and the due-process principle, in that it effectively hollowed out the duty to prepare and deliver a detailed list of the seized electronic information and the duty to delete, discard, or return unrelated information. It judged that merely presenting a simple list at the suspect interrogation could not be regarded as curing the unlawfulness (Suwon District Court, Jan. 13, 2025, 2024no2446).

4. The Substantive Structure of the Standard — Comprehensive Summary

Analyzing the above cases, the key factors the courts substantively consider when assessing whether there is an “infringement of the substantive content of due process” and a “conflict with criminal-justice justice” may be summarized as follows.

Factor	Toward recognizing the exception	Toward denying the exception
Intentionality of the violation	A violation by mistake or carelessness	An intentional, deliberate violation
Infringement of the warrant requirement	The essence of the warrant requirement not infringed	A head-on violation of the warrant requirement—a warrantless compulsory measure, separate-case seizure, etc.
Substantive infringement of the defendant’s rights	The defendant could substantively exercise his rights	Substantive deprivation of the defendant’s defense right or right to contest
Avoidability of the violation	Hard to avoid given the on-scene situation	Sufficiently avoidable, e.g., by applying for an advance warrant
Result of excluding the evidence	Exclusion would bring about a clearly unjust result	Exclusion rather accords with guaranteeing due process
The agency’s after-the-fact measures	Effort to immediately correct after recognizing the violation	Leaving the unlawful state, or a further violation

In scholarship in particular, the practical difference between the “infringement of the substantive content of due process” standard presented by the majority opinion in the Supreme Court en banc judgment 2007do3061 and the “grave unlawfulness that nullifies the spirit and purport of the warrant requirement” standard presented by the separate opinion has been discussed; but there is also an assessment that, in the actual operation of the precedents, the two standards tend to converge on similar conclusions. That said, the point that a substantive difference in the judge’s judgment may arise depending on which standard is adopted still needs to be borne in mind.

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