“Gathered Evidence of an Affair Only to Face a Criminal Complaint in Return”…What Are the Key Standards in Collecting Evidence of Infidelity?

The Namyangju Branch of the Uijeongbu District Court on May 22, 2026, sentenced the defendant, who had been prosecuted on charges of violating the Protection of Communications Secrets Act, to eight months' imprisonment, suspended for two years, together with one year of suspension of qualifications.

In that case, the defendant was prosecuted on the charge that, suspecting her husband's infidelity, she installed a subminiature voice recorder under a table in a shared office and secretly recorded conversations between her husband and his acquaintances.

The court found that “secretly recording the contents of a conversation between others infringes the privacy and freedom of an individual's private life guaranteed by the Constitution.”

On February 26, 2015, the Constitutional Court pronounced a decision of unconstitutionality on Article 241 of the Criminal Act, which had defined the crime of adultery (Constitutional Court, Decision of February 26, 2015, 2009 Heonba 17, etc.).

Since then, the issue of infidelity has shifted to a structure resolved not through criminal punishment but through civil proceedings, such as divorce litigation and affair-partner litigation.

The problem is that, in many cases, the party asserting the fact of infidelity must directly prove the wrongful act.

Materials related to infidelity often exist within the domain of personal privacy, such as text messages and messenger conversations on a mobile phone, vehicle travel routes, and call records, so victims frequently find themselves in situations where they try to secure evidence directly.

In this process, methods such as installing a voice recorder in a vehicle, examining a mobile phone without authorization, attaching a location tracker, or photographing messenger contents may become the subject of a criminal complaint, including a violation of the “Protection of Communications Secrets Act,” the “Act on Promotion of Information and Communications Network Utilization and Information Protection, Etc.,” or the “Act on the Protection, Use, Etc. of Location Information.”

In other words, there are cases in which, after securing evidence of infidelity, a person is in return investigated on charges such as violation of the Protection of Communications Secrets Act, illegal filming, or unauthorized intrusion, so caution is required as to the manner in which evidence is secured.

According to an article reported by The Dong-A Ilbo on May 15, 2026, in a case pronounced by the Supreme Court on April 30, 2026, the plaintiff had installed a voice recorder in the spouse's vehicle and recorded conversations, and had also photographed text messages, photographs, and videos on the spouse's mobile phone, submitting them as evidence in the affair-partner litigation.

In response, the Supreme Court, considering the need to prove infidelity and the status of the ongoing divorce litigation, recognized the use of the mobile-phone photographs as evidence.

By contrast, it did not recognize the use, as evidence, of the conversation contents secured by means of the vehicle voice recorder.

Article 3, Paragraph 1 of the “Protection of Communications Secrets Act” provides that no one may record or listen to an undisclosed conversation between others, and Article 4 of the same Act provides that conversation contents unlawfully obtained may not be used as evidence in a trial or disciplinary proceeding.

Accordingly, the Supreme Court determined that recording a third party's conversation by means of the vehicle voice recorder constituted unlawfully collected material and did not recognize its use as evidence.

The “Protection of Communications Secrets Act” restricts the act of recording or listening to an undisclosed conversation between others, and the “Act on the Protection, Use, Etc. of Location Information” regulates the issue of collecting location information without consent.

In addition, where a person examines a spouse's mobile phone at will or installs a wiretapping app or the like, there is also a possibility that an issue of violating the “Act on Promotion of Information and Communications Network Utilization and Information Protection, Etc.” may be reviewed together.

Where unauthorized intrusion or filming of a private space is also carried out in the course of securing evidence, there is a possibility that additional charges may become an issue as well.

Accordingly, in affair-partner litigation or divorce litigation, what matters is not only proving the fact of infidelity but also whether the process of securing the materials itself was carried out in a lawful manner.

Daeryun Law Firm LLP, through collaboration with its 🔗Evidence Investigation Center, jointly analyzes the process of securing the materials at issue and the structure of the evidence in infidelity and affair-partner cases.

In addition, where a criminal-complaint issue follows alongside the affair-partner litigation, it comprehensively reviews the civil and criminal proceedings through collaboration with criminal attorneys and organizes the direction of response.

If you need assistance with securing evidence or with a criminal complaint in an infidelity or affair-partner case, we invite you to review the response direction suited to your circumstances through a 🔗Legal Consultation Reservation.