Without evidence of infidelity, can I not proceed with a lawsuit against the third party?

A damages claim lawsuit against a third party (the so-called "lawsuit against the third party"") under Article 750 of the Civil Code, etc. cannot be filed based on mere suspicion or circumstances. To establish the lawsuit, it must be proven that an act of infidelity actually existed between the spouse and the third party.

In other words, if there is no legally recognized "evidence of infidelity," even if a lawsuit is filed, the plaintiff's claim is unlikely to be accepted.

The key elements that the court considers in such lawsuits are the following three:

① Whether the third party was aware that the other party's spouse was married

② Whether infidelity continued between the two parties despite this

③ Whether the plaintiff suffered mental distress due to that infidelity

Various evidence can be collected by ordinary people to prove these three elements.

For example, if text messages or messenger conversations contain expressions of affection or circumstances of secret meetings, they can be very strong evidence.

In addition, motel entry photos, vehicle dashcam footage, location records, etc. can also be used as circumstantial evidence supporting infidelity.

Mental distress can be proven through depression diagnosis, counseling center records, statements from family or acquaintances, etc.

In particular, the fact that the third party was aware that the other party was a married man is an essential requirement for recognizing tort liability (refer to Supreme Court Decision 87Meu19).

If there is no material proving such awareness, the court may deny intent or negligence and dismiss the damages claim.

Accordingly, recordings hinting at or mentioning marital status in conversations with the other party, statements from acquaintances supporting awareness of the marital fact, public documents or circumstantial evidence, etc. become important judgment materials.

In conclusion, lawsuits against the third party filed without substantive evidence of infidelity may have significant legal limitations, and thorough collection of evidence of infidelity should be prioritized before lawsuits.