A lawsuit to confirm the existence of a biological relationship is a lawsuit to confirm whether a legal biological relationship exists or does not exist between a parent and a child.

If there is a dispute regarding the biological relationship, such as when the person listed as biological is not actually biological, or when the biological relationship is not reflected in the family relationship register, the legal relationship can be confirmed through a lawsuit to confirm the existence of biological relationship.

Typically, a lawsuit to confirm the existence of a biological relationship is used in the following cases:

• If a person who is not the actual biological child is registered as a child due to a false birth report
• In cases where the paternity is not reflected in the family relationship register even though the child is biological.
• If the child is incorrectly listed in the family relationship register as a child of someone other than the biological parent.
• When it is necessary to confirm or deny paternity for a child for whom the presumption of paternity is not possible

A lawsuit to confirm the existence of a biological relationship can be filed by any person who can file a lawsuit for the father's decision by the court (Article 845 of the Civil Act), denial of the child's paternity (Articles 846, 848, 850, and 851 of the Civil Act), objection to recognition (Article 862 of the Civil Act), and request for recognition (Article 863 of the Civil Act) (Article 865 (1) of the Civil Act).

In other words, it can be filed by the father or mother, children, legal representative, and certain interested parties.

An action to confirm the existence of a biological relationship is an action for confirmation, and there is no limitation on the period for filing a lawsuit. However, when one of the parties dies and a lawsuit is filed with the prosecutor as the other party, the lawsuit must be filed within two years from the date of knowledge of the death (Article 865, Paragraph 2 of the Civil Act).

Additionally, when a third party files a lawsuit, if both parties subject to confirmation of biological relationship are deceased, the lawsuit must be filed ‘within two years from the date of knowledge of the death of both parties’ (Supreme Court ruling 2003M2503, February 12, 2004).

An action to confirm the existence of a paternity relationship cannot be filed simply to confirm the truth of the paternity relationship, but can only be filed if there is a legal interest in obtaining a confirmation ruling.

The benefit of confirmation means that one's legal status, etc. will be directly affected by an error in the paternity relationship between other people. In other words, the mere fact of a relative relationship does not necessarily mean that a lawsuit can be filed to confirm the existence of a biological relationship, and when an interested party, including a relative, files a lawsuit, they must claim and prove that there is a separate benefit to the confirmation.

Once a judgment accepting a request for confirmation of biological relationship is confirmed, the judgment has effect not only on the parties but also on third parties (Article 21, Paragraph 1 of the Family Litigation Litigation Act). If the judgment rejecting the claim becomes final, the other person with the right to file a lawsuit cannot file a lawsuit again unless there is a justifiable reason for failing to participate before the conclusion of the argument in the factual trial (Article 21, Paragraph 2 of the Family Litigation Act).

Once the ruling confirming the existence of a biological relationship is finalized and becomes effective, the parties concerned will apply for correction of the family relationship register (Article 107 of the Family Relationship Registration Act, etc.) to correct the records in the family relationship register.

If it is determined that the records in the family relationship register cannot be permitted by law or that there are errors or omissions in the records, the interested party may apply for correction of the register with permission from the family court having jurisdiction over the place of registration of the person in question (Article 104 (1) of the Family Relationship Registration Act, etc.).

However, this is limited to cases where the correction is minor, and if the correction has a significant impact on the kinship law or inheritance law, such as birth, death, marriage, expulsion due to marriage, paternity, mother's domicile, etc., the correction cannot be made without a final judgment (Supreme Court decision dated May 8, 1987, 86S29, 30, 31).

Therefore, if the paternity relationship in the family relationship register is recorded differently from the actual relationship, a lawsuit to confirm the existence of the paternity relationship will be filed and a judgment will be received, and then the family relationship register will be corrected according to the final judgment.