Since 1 April 2026, a Japanese court can name both parents as holders of parental authority after divorce. Most English-language summaries stop there. The part that decides whether it works for you — what joint authority obliges you to do, and what happens when one parent lives outside Japan — is barely written about in English, and thinly written about in Japanese.
“Custody” and “parental authority” are two different things here
English-speaking parents arrive with one idea: custody. Japanese law splits it in two.
Parental authority (shinken) is the legal power to decide about the child — where the child lives, education, medical treatment, and acting for the child in legal matters (Civil Code arts. 820–824).
The person designated to have care of the child (kangosha) is who the child actually lives with day to day. Where a kangosha has been designated, that person holds the same rights and duties as a holder of parental authority for care and education, choice of residence and permission to work, and may exercise them alone (art. 824-3).
The two can sit with different people. You can hold parental authority and not have the child living with you. You can be the kangosha without holding parental authority. When a Japanese lawyer asks which one you are asking about, this is why.
What the 2026 amendment changed
Before, a divorce in Japan ended with exactly one parent holding parental authority. Now:
- Divorce by agreement: the parents decide in their agreement whether one or both of them will hold parental authority (art. 819(1)).
- Divorce through the court: the court decides whether one or both will hold it (art. 819(2)).
Where the court makes that decision, art. 819(7) sets a two-part test.
First, the court must name only one parent where naming both would harm the child’s interests. The provision gives two examples:
- where a parent is found to present a risk of harm to the child’s mind or body;
- where, taking into account the risk of violence or other conduct harmful to mind or body by one parent toward the other, the reasons the parents’ agreement failed, and other circumstances, it is found difficult for the parents to exercise parental authority jointly.
Second, in every other case the court weighs the relationship between each parent and the child, the relationship between the parents, and all other circumstances, in the child’s interests.
Two things follow that are commonly misread.
There is no presumption either way. Joint authority is not the rule and sole authority is not the exception. The court decides on the case in front of it.
Violence is not limited to physical violence. The statute says “violence against the body or other conduct causing harmful effects on mind or body”. The commentary from the Tokyo Family Court reads this as covering psychological, economic and sexual abuse as well.
What joint parental authority actually obliges you to do
This is the part that decides whether joint authority is workable, and it is set out in art. 824-2.
The rule is joint exercise. Where both parents hold parental authority, they exercise it together.
Three exceptions let one parent act alone:
- where only that parent holds parental authority;
- where the other parent is unable to exercise it;
- where there are urgent circumstances for the child’s benefit.
Day-to-day acts of care and education can always be done alone. Even where both parents hold authority, either may act alone on the ordinary business of raising the child (art. 824-2(2)). Nobody has to telephone Ohio about a haircut.
Where the parents deadlock on one specific matter, the family court may, on the application of either parent, rule that one of them may decide that particular matter alone (art. 824-2(3)). This is the provision to know about. It is not all-or-nothing: you do not have to return to court to undo joint authority in order to resolve a single decision.
The question nobody has answered yet: when one parent lives outside Japan
Here is where we have to be careful with you.
Exception 2 above — “where the other parent is unable to exercise it” — is the provision a parent living overseas will immediately think of. Whether living outside Japan falls within it has not been settled. We have read the Tokyo Family Court’s three-part commentary on the amendment in full. It does not address foreign parents, cross-border cases, or a parent living abroad. Neither does the Ministry of Justice material. There is no case law yet to read, because the provision is five months old.
So we will not tell you the answer, because there is not one to give. What we can tell you is what the friction looks like in practice, because it is predictable:
- Decisions that need both parents do not wait for time zones. A school enrolment deadline, a surgical consent, a passport application.
- A signature from abroad often needs notarisation or consular certification, which adds days or weeks.
- The reason the agreement failed is itself a factor the court weighs under art. 819(7). Distance and language are not on the statutory list — and we will not claim the courts will read them in.
What we do about it is concrete. Where joint authority is being agreed, we set out in the agreement which categories of decision require both parents and which do not, and how notice is to be given, so that the arrangement is capable of running from two countries. Where a deadlock has already happened, art. 824-2(3) exists for exactly that.
If you divorced before 1 April 2026
A parent who holds sole parental authority under the previous law can apply to the family court to change it (art. 819(6)). We want you to read the next three paragraphs before you decide to.
The amendment coming into force is not, by itself, a change of circumstances. The Tokyo Family Court commentary is explicit: the fact that the new law now exists does not on its own justify changing an arrangement already made. The court starts from the position that sole authority was decided, and asks what has changed since.
The court looks at what happened after the divorce, not at what would have happened at the time. The question is not “would joint authority have been chosen if the new law had existed then”. It is whether the situation now makes joint authority better for the child. In practice the court will look at: whether living apart has become settled and enough time has passed for conflict to subside; how the parents have handled contact and child support between them; how they have discussed matters concerning the child; and whether each has shown regard for the other.
Where the other parent objects, the hurdle is higher than for parents divorcing now. We say this plainly because the opposite is being said elsewhere. An agreement made before the amendment that the parents would “switch to joint authority once the law changes” does not take effect by itself either — it has to be agreed again in mediation, or decided by the court.
One point cuts in your favour, and it is in the statute. Where the original arrangement was made by the parents’ own agreement, art. 819(8) directs the court to consider how that agreement was reached — including whether there was violence, whether mediation or out-of-court dispute resolution was used, and whether the result was recorded in a notarial deed. How you documented things then affects what you can do now.
What we can and cannot tell you
We can tell you what the statute says, what the family court’s published commentary says, and what it does not say. On the cross-border questions, the honest answer today is that the Japanese legal literature has not reached them yet. We will tell you which parts of your question have an answer and which do not, and we would rather do that in the first thirty minutes than after you have instructed us.
Yusuke Sasaki handles these matters in English. The first 30 minutes are at no charge.
Read next: Child support in Japan after divorce — what changed on 1 April 2026. Which of the three changes reaches back into an arrangement you already have, and what the courts require before they will act on it.
Read next: Is a Japanese divorce by agreement valid in your country? Whatever you agree about the children, it is recorded in a Japanese filing — and your own country may not treat that filing as a divorce at all.
The Civil Code provisions referred to on this page can be read in Japanese at e-Gov. This page describes the law in general terms and is not advice on your situation.