On April 1, the Hague Convention on the Civil Aspects of International Child Abduction went into force in Japan, as did the necessary implementing legislation. Having already written about this legislation in a prior column, I won't revisit the subject here.

While Japan's accession is a welcome step forward, I wonder how it will actually pan out. Implementation may be frustrated by some basic features of Japanese family law that can be neatly described mathematically: 1+1=1.

I would love to take credit for this wonderfully expressive formula, but it comes from a Japanese lawyer I met a few months ago, who used it to explain his own doubts about the convention's viability here: "To Westerners, marriage means 1+1=2. But in Japan it equals 1." It made perfect sense to me, but perhaps I should explain.