Adultery Claim Defense: 600 Million Won Reimbursement Demand Reduced to 40 Million Won

Taeshin Law Firm represented a married woman who was sued by her former partner for reimbursement of the full amount of two settlements he had paid to her husband after their extramarital relationship was discovered. Relying on a written undertaking the partner had created using the client's identification and seal, he demanded the return of 600 million won. The court held that the undertaking was void as contrary to public order and good morals, and limited the client's liability to her one-half share of the ordinary consolation money, ordering payment of 40 million won and dismissing the remainder of the claim. The demand was reduced by 560 million won, and the plaintiff bore 95% of the litigation costs.

Background / Issue

The client was a married woman. The plaintiff, a man, carried on a relationship with her from around 2013 until August 2022, knowing that she was married.

In November 2018, the client's husband discovered the relationship. The plaintiff wrote a settlement agreement with the husband and paid him consolation money. The agreement contained a clause requiring the plaintiff to pay a large penalty if he contacted the client again.

The plaintiff later used the client's identification card and personal seal, which he had obtained from her, to create a separate written undertaking stating that, if the husband demanded money, the client would pay the plaintiff the same amount.

When the relationship was discovered again, the husband sued the plaintiff to enforce the penalty, and the plaintiff paid a second settlement in May 2024. The plaintiff then claimed 600 million won from the client — the full amount of both settlements.

Legal Issues: The case raised two main questions. First, whether an agreement entered into for the purpose of continuing an extramarital relationship is enforceable; under Korean law, an agreement whose purpose is contrary to public order and good morals is void. Second, to what extent the parties share liability for consolation money paid to the spouse — where one party pays the full amount, that party may seek the other's share, but the recoverable amount is generally limited to the ordinary consolation money.

Our Legal Approach

Taeshin Law Firm argued that the written undertaking had been created for the purpose of freeing the plaintiff from the penalty burden and allowing the relationship to continue, and that it was therefore void as contrary to public order and good morals. The defense team set out the sequence of events in chronological order to show that purpose, and established that the plaintiff had created the undertaking only after his request for security had been refused.

The team also contested the plaintiff's claim that the client had conspired with her husband to threaten the plaintiff and extract settlement money, and made clear that the only parties to the settlement agreement were the plaintiff and the husband.

Result / Outcome

In May 2026, the court accepted the client's defense and held that the undertaking was void because it had been written for a purpose contrary to public order and good morals. The court rejected the plaintiff's argument that asserting invalidity amounted to an abuse of rights, and also rejected the claim that the plaintiff had been threatened into paying the settlements.

The court treated the consolation money for which the parties shared responsibility as 30 million won for the first settlement and 50 million won for the second, and fixed the client's share at one half of each. The client was ordered to pay 40 million won plus interest, and the rest of the claim was dismissed. The 600 million won demand was thus reduced to 40 million won, and the plaintiff bore 95% of the litigation costs.

Why This Case Mattered: This case illustrates how Korean courts examine agreements connected to extramarital relationships. Even where liability exists, it is generally shared between the parties, and the recoverable amount is limited to the ordinary consolation money rather than the full settlement paid to a spouse. It also shows that a written undertaking created to continue an unlawful relationship may be challenged as void.

Results depend on the specific facts and circumstances of each case. Past results do not guarantee a similar outcome.