Japan may sign the Hague Convention, but if planned new laws for ratifying the treaty fail to compel family court judges to adhere to its principles, the whole exercise could be meaningless, legal experts and people whose children have been victims of parental abductions say.

"The legal principle of the Hague Convention is to always return the child unless there is clear and convincing evidence that this default presumption of return can be rebutted because of imminent danger of grave harm to the child," said Christopher Savoie, a Tennessee resident whose Japanese former wife illegally took the couple's children to Japan.

"That rebuttal can and should be very hard to prove in court."