A new lawsuit questioning the constitutionality of Japan’s system to force married couples to use the same surname underscores afresh the absence of good reason for the requirement.

It also widens the scope of criticism against the system by adding new viewpoints.

One of the plaintiffs in the suit, filed in Tokyo District Court on Jan. 9, is a businessman who has changed his surname upon marriage.

The difficulties and disadvantages involved in having to change your surname, including the required change in your name used for legal documents, and the sense of losing part of your identity, can also be a serious problem for men as well as for women. This obvious fact has been brought forcefully to the consciousness of our society by his legal action.

What is especially notable about the lawsuit is the plaintiffs’ argument that a provision of the Family Register Law, which allows Japanese-foreigner couples to choose different surnames but not Japanese couples, is unconstitutional.

Since foreigners are not on a family register in Japan, Japanese-foreigner couples usually use different surnames. But they are allowed to adopt the same name if they wish to do so.

In contrast, the only option for Japanese couples is to choose either of their names. The plaintiffs argue that this is a shortcoming of the law and violates equality under the Constitution.

Opponents of the proposal to allow married couples to use different surnames often say the step would undermine the integrity of families.

If they were right, many of the more than 20,000 foreigner-Japanese marriages that are made every year should collapse.

The reality clearly shows how preposterous this argument is.

Around the time the lawsuit was filed, Yuko Miyazaki, a former lawyer who has become a Supreme Court justice, attracted public attention by declaring that she will continue using her maiden name for professional purposes as she has been doing so far.

Her choice has been made possible by a Supreme Court decision last year to allow the use of premarital names in legal documents such as judgment documents and indictments.

Wider use of original family names is being promoted by the government, which is seeking to expand the role of women in society.

Ministries and agencies are taking steps in line with the government’s policy.

We have no objection to this campaign itself. But it is actually an odd way to deal with the issue.

Legally, a premarital name is treated only as the name the person is commonly known by. But the current approach allows officials to use such “informal” names in important legal documents, including judgment documents that may sentence someone to death and documents concerning policy decisions that have huge implications for people’s lives and business activities.

Some may end up using their “informal” premarital names in most cases while barely using their legal names on the family register.

It is hard to fathom the reason for sticking to the current system even by adopting this complicated approach, which could raise doubts about the legitimacy of actions taken in exercise of power.

There would be advantages and disadvantages for married couples in either using the same surname or different ones. But there is no compelling case against allowing married couples to make the choice on their own.

About two years ago, in reference to using separate surnames for married couples, the Supreme Court ruled that the Civil Law provisions requiring of a common name shared by a husband and wife was deemed constitutional.

But the top court said the ruling didn’t mean the idea of allowing married couples to use different surnames was unreasonable. It called on the Diet to debate the issue and make its decision.

Controlled by the Liberal Democratic Party, which upholds conservative ideas about families, the Diet has been slow to tackle this issue.

But the current system is causing problems in society. The latest lawsuit should lead to fresh public debate on this issue.

--The Asahi Shimbun, Jan. 16