A reader wrote in asking for some advice on issues related to paternity and marriage:

I am a foreign woman, married to a Japanese man. However, now I am pregnant, and my husband is not the father of my baby. His/her biological father is another man.

Can my baby use the family name of his/her biological father? I want my baby to use the name of his/her true father, not of my husband. I hope you can answer my question.

According to Japan’s Civil Code, a child conceived by a wife during marriage is legally presumed to be the child of her husband. Therefore, even if another man is the biological father, when the wife registers the birth, as she is legally required to do, the baby automatically enters her family register as the husband’s child. In this situation, the baby is only able to use the husband’s surname.

In the event that the baby’s biological father is Japanese, before the child can take that man’s surname, the parties concerned need to go through the following three procedures:

1) Rebuttal of the presumption that the child was born in wedlock.

2) Acknowledgement of paternity by the biological father.

3) Reacquiring Japanese nationality.

Let’s look at these steps one by one.

Rebutting the presumption that the child was born in wedlock

A Japanese biological father can acknowledge his own child in this kind of case only when the child is recognized as having been born out of wedlock. To rebut the legal presumption that the child was born in wedlock, the husband must file for mediation proceedings with the family court after the birth of the child.

It’s important to note that this particular mediation process — known as chakushutsu hinin chōtei (mediation to deny legitimacy) — can only be filed by the husband, and this must be done within a year of the child’s birth. The privileged position of the husband in these cases was the focus of a recent Osaka High Court case, which upheld the constitutionality of the status quo.

In these proceedings, when the husband and the wife are in agreement that the baby is not the husband’s, the family court would then investigate the facts of the case, usually by requesting DNA tests, before issuing a conclusion that the baby is not the husband’s child.

If the wife believes she can prove that it was impossible for her to conceive her husband’s child — such as if the couple had not met for a long time at the point she became pregnant — she can file for mediation proceedings (oyako kankei fusonzai kakunin chōtei) to have the court deny the parental relationship between her baby and the husband. In this kind of case, a mother can file for mediation even after more than a year has passed since the child was born.

Acknowledgement by the biological father

After a court has issued a conclusion denying the child was born in wedlock, the child is in a position to be acknowledged by his/her biological father. The father can acknowledge his child by filling in paperwork at his local municipal office or by filing for acknowledgement proceedings in a family court. If he goes the court route, the procedure for acquiring Japanese nationality for the child could turn out to be easier, as less documentation is needed.

Acquiring Japanese nationality

A child loses Japanese nationality with the conclusion by the court that he/she was born out of wedlock. This means the mother has to go through certain procedures for the child to regain citizenship.

A child born of a Japanese father outside of marriage and acknowledged by that father is able to acquire Japanese nationality.

After the child acquires citizenship, only then, finally, can the child choose to use the surname of his/her biological father.

If the biological father is not Japanese

If the biological father is a foreign national, first, the Japanese husband still needs to go through the first procedure and rebut the presumption that the child was born in wedlock.

After this, things get more complicated. When it comes to stage two — the acknowledgement by the biological father — the baby may also be able to go through this procedure in Japan. According to Japanese law, the legislation governing the acknowledgement could be the father’s country’s domestic law at the time of the child’s birth or either the father or the child’s domestic law at the time of the acknowledgement itself.

In some countries it may also be necessary to obtain the acceptance or consent from the child or a third party to make the acknowledgement legal under a foreign parent’s home-country law at the time.

Finally, even when the child has been acknowledged by his/her biological father, whether or not that child can use this man’s surname depends on the case, or, more specifically, on the national laws of the countries concerned.

Regarding all these issues, non-Japanese parents should consult their embassies or other trusted sources for further information. If the biological parents are from different countries, obviously the laws of both countries will have to be taken into account.

Natsumi Fujii is an attorney with the Foreign nationals and International Service Section at Tokyo Public Law Office, which handles a wide range of cases involving non-Japanese in the Tokyo area (03-5979-2880; www. t-pblo.jp/fiss) FISS lawyers address legal queries received by Lifelines. Send all your questions and other comments to lifelines@japantimes.co.jp.

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