The Communication Security and Surveillance Act Article 17

The information obtained from the communication surveillance should be sealed or otherwise marked, and stamped by the enforcement authority to preserve its true completeness without addition, deletion or change. Information used as case evidence shall be kept in the file, or otherwise kept for as long a time as is necessary for surveillance purposes. The enforcement authority should safe-keep the information for five years after the communication surveillance is completed, and destroy it afterwards.For information obtained from the communication surveillance that is completely irrelevant with the surveillance objective, the enforcement authority should submit a report to the prosecutor, the judge who issued the interception warrant ex officio or the head of the authority overseeing national intelligence, and destroy the information after gaining their approval.When destroying the information as described in the preceding two Paragraphs, the enforcement authority should record the facts concerning the communication surveillance, and submit a request to the prosecutor, the judge who issued the interception warrant ex officio or the head of the authority overseeing national intelligence to dispatch an on-site representative.