When is a search of a suspect's messages held on an internet service provider's server unlawful enough to be cancelled? Decision 2016Mo587 (31 May 2022) on grave unlawfulness in the search procedure

Question

Articles 121 and 122 of the Criminal Procedure Act provide that the prosecutor, the defendant or counsel may participate in the execution of a search and seizure warrant, and that the date and place of execution must be notified to those persons in advance, except where a person has expressly stated an intention not to participate or where 'speed is required'. Article 129 requires a list of seized items to be delivered to the owner, possessor, custodian or a person of similar standing, Article 215(2) and Article 219 govern a judicial police officer's search and seizure, and Articles 417 and 415 set out the petition for review and the further appeal. When investigators execute a warrant against an internet service provider and take a suspect's electronic information from the provider's server, the question is which of these duties bind them at each stage, and how grave a breach must be to cancel the search and seizure.

Decision 2016Mo587 raises that question on a warrant issued for a suspect's KakaoTalk messages held on the server of the internet service provider Kakao. The investigators faxed the warrant to Kakao, which sent them every message for a two-day period, including everyday conversations unrelated to the suspicion; the suspect was given no notice and no chance to take part, the whole data was printed and seized without selection, and no inventory was delivered. The suspect asked for the search and seizure to be cancelled, and the prosecutor appealed the order granting that request.

Material to check

The statutes are Articles 121, 122, 129, 215, 219, 415 and 417 of the Criminal Procedure Act. Article 121 allows participation in the execution of a warrant; Article 122 requires advance notice of the date and place of execution to the persons in the preceding article, save where one has stated an intention not to participate or where 'speed is required'; Article 129 requires a list of seized items to be prepared and delivered to the owner, possessor, custodian or a person of similar standing. Article 215(2) lets a judicial police officer seize, search or inspect, on a warrant issued by a district court judge at the prosecutor's request, limited to what is recognised as related to the case and where there are circumstances suggesting the suspect committed a crime; Article 219 applies listed provisions, including Articles 118 to 132, to such work. Article 417 allows a petition for review to cancel or change a prosecutor's or judicial police officer's measure on detention, seizure or return of seized property, and Article 415 allows an immediate appeal to the Supreme Court from a decision of the appellate court or a high court only on the ground of a violation of the Constitution, a statute, an order or a rule affecting the judgment. The current text, effective 2 October 2026, records that Article 215(1) was deleted on 4 August 2026 and that Article 219 was wholly revised on the same day.

The decision is Decision 2016Mo587 (31 May 2022), an order of the Supreme Court on the prosecutor's appeal. The order below is that of the Seoul Central District Court of 18 February 2016 (2015Bo6), which cancelled the search and seizure. The decision states its facts and the parties' positions in its own reasons; it cites no earlier decision.

Possible readings

Read with the reasons of Decision 2016Mo587, the question whether a search and seizure is cancelled for unlawfulness is answered by looking at the defects in combination and asking whether they are grave enough to make the whole search procedure unlawful. The decision approved cancellation where four defects were added together: the warrant original was not shown to the party subject to the measure, the electronic information taken from the provider was printed and seized as evidence without any selection of the parts related to the suspected facts, the complainant was given no participation right, and no list of the seized electronic information was delivered.

A second reading follows from the decision's treatment of the person whose data was held. The complainant was the service user whose messages were stored on the provider's server, and the decision describes him as the real subject of the seizure and a suspect, and finds that his participation right was not secured, both in the search and in the later examination and printing of the electronic information obtained from the provider. The decision found that failure unlawful, so taking the data from the provider did not by itself give the complainant the participation the procedure required of him.

A third reading concerns the notice exception. The court below held that the case was not one where 'speed is required' under the proviso to Article 122, so the failure to notify the date and place of execution in advance and to secure the participation right was unlawful. The decision held that this part of the court below's reasoning was wrong, but went on to approve the outcome on the four defects it listed. It did not hold that any one of those defects alone would cancel a search.

What the decisions held

A judge of the Seoul Central District Court issued the warrant on 24 May 2014 at the prosecutor's request, naming the complainant as the suspect and listing a mobile phone handset and KakaoTalk account information, chat contents, photographs and video exchanged from 12 May 2014 to 21 May 2014 as items to be seized. The places to be searched were the complainant's body (only if submission was refused), a bag or clothing where the phone was likely kept, and Kakao's head office or the data centre holding the items; the suspicion recorded was violation of the Act on Assembly and Demonstration, including breach of an organiser's duties. On 26 May 2014 at about 11:55 the investigators executed the warrant against Kakao, sending it by fax only and not showing the original. Kakao's officer extracted every conversation of the complainant from 00:00 on 20 May 2014 to 23:59 on 21 May 2014 and sent it by email, because the information related to the crime could not be separated out; the data included the complainant's everyday conversations with parents and friends. The investigators gave no advance notice of the date and place of execution, so the complainant did not take part, and they gave no opportunity to participate while the data was searched and printed; they printed and seized the whole without selection. After execution they delivered no inventory to Kakao or to the complainant.

The court below held that the search was not one where 'speed is required' under the proviso to Article 122, so the failure to notify the execution date and place and to secure the participation right was unlawful; and that, given the circumstances, the complainant's remaining arguments, including presentation of the warrant original and delivery of a list of seized items, did not need to be examined further, and the search and seizure could not escape cancellation.

The Supreme Court dismissed the prosecutor's appeal. It held that the court below was wrong to say that obtaining the electronic information by executing the warrant against Kakao did not fall within the 'speed is required' exception in the proviso to Article 122. Even so, it approved the conclusion that the unlawfulness shown in this search was grave enough to make the whole search procedure unlawful and to cancel the search and seizure, taking together the failure to present the warrant original, the printing and seizure of the whole information without selecting the parts related to the suspected facts, the failure to secure the participation right of the complainant as service user, real subject of the seizure and suspect, and the failure to deliver the list of seized electronic information. It therefore found no violation of the Constitution, a statute, an order or a rule affecting the judgment. The order was unanimous, with Justices Oh Kyung-mee presiding, Park Jung-hwa, Kim Sun-soo reporting and Noh Tae-ak.

Points left open

The decision does not say which of the four defects it lists would be enough on its own. It approved cancellation on the strength of their combination and disagreed with the court below on one point of law, so a case with one defect only, such as failure to show the warrant original or failure to deliver an inventory, is not answered.

The decision also leaves open the scope of the 'speed is required' exception in the proviso to Article 122 for electronic information held on an internet service provider's server. It held that the court below was wrong on that point but did not set out what notice and participation remain due once the exception applies, nor did it rule on the evidentiary effect of data obtained by a cancelled search; its order concerns only the cancellation of the search and seizure under Article 417.

When to reconsider

We revisit this brief if the Supreme Court rules on what the 'speed is required' exception covers for server-held electronic information or on whether any single defect cancels a search, if it rules on the evidentiary effect of data obtained by a search later cancelled, or if Articles 121, 122, 129, 215 or 219 of the Criminal Procedure Act are amended again.

Statutes referred to

• 형사소송법 제121조, 제122조, 제129조, 제215조, 제219조, 제415조, 제417조

Decisions referred to

• 대법원 2022. 5. 31. 자 2016모587 결정 · Decision ledger

Verification status

All texts were read at the National Law Information Center (law.go.kr) on 24 October 2026. The decision was read in its published headnote, summary and reasons, and the seven articles of the Criminal Procedure Act it cites in their current text.