The Australian submission encouraged Japan to introduce family law which establishes shared parenting arrangements. Australia’s Ambassador to Japan Justin Hayhurst raised the issue with Justice Minister Ken Saito on March 14.

Australian officials view the opening of submissions to international parties as a significant sign that Japan is paving the way for legislative change, but they have been reluctant to publicly criticise Japan - one of Australia’s closest diplomatic, military and economic partners.

Masahiko Shibayama, the deputy secretary-general of Japan’s ruling Liberal Democratic Party, said he had called for the Foreign Ministry to join a committee looking at reforming Japan’s sole custody laws.

“This means it will not only be the police or the Justice Ministry,” he said. “This way the government must cooperate with each other to make a good decision, not only for domestic but also international reasons.”

Shibayama, the education minister in Shinzo Abe’s government, said the former prime minister was keenly aware of the toll it was taking on Japan’s international standing after Japan’s position was criticised in a meeting with French President Emmanuel Macron.

He said Japan’s Prime Minister Fumio Kishida had been made aware of the damage the system was doing.

“I think the process of changing the law is on the way now,” Shibayama said. He had earlier labelled the sole custody system “an embarrassment”.

Officials inside Japan’s Ministry of Justice, who were not authorised to speak publicly, said they were considering a split system of joint and sole custody.

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Joint custody could be awarded to parents where there is no evidence of domestic violence, while sole custody would be awarded to those fleeing violent relationships.

The Justice Ministry is also considering whether to award joint custody to foreign parents that split from a Japanese partner in a move that would help hundreds of foreign parents who are separated from their children each year.

In the case of a foreign parent, the custody law could be applied from their home country, creating a legal minefield for the department.

Officials said they were seeking advice from other countries, including Germany and Australia, about how their joint custody system operates as they grapple with mounting domestic violence cases and poor social services infrastructure.

“We need to come up with something that is suited to Japan,” said one Japanese official.

“Family law, civil law, this is something really, you know, that concerns every single person. So, I think it requires various levels of discussions. This really requires everyone’s understanding. That’s why time is needed.”

A dozen Australian parents say they have not been able to see their children despite some having court orders guaranteeing them access to their children. They have accused the Japanese and Australian governments of failing to act after 20 years of evidence of abductions across Japan.

The Japanese Ministry of Justice official said he was aware of the courts and police failing to enforce visitation orders.

“Even if you bring this up to the court - they’re not able to meet their child, I am fully aware of it,” he said. “How can we strengthen the enforcement? That is also another one of the topics we’re discussing.”

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The issue has become a domestic political flashpoint in Japan as domestic violence advocates argue that sole custody is the only legal protection that survivors have to flee abusive relationships.

However, a poll by Fuji TV last year found 72 per cent of Japanese respondents favoured joint custody, 13 per cent were against and 15 per cent had no opinion.

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