Tokyo, Japan: Japan's Supreme Court on Wednesday upheld a law that married couples must have a common surname, a defeat for campaigners who have blasted the 19th century statute as sexist and archaic.

The top court's Grand Bench -- its highest ruling body -- said the law did not violate the constitution, broadcaster NHK and other Japanese media reported.

The ruling is likely to satisfy conservatives who call it essential to maintaining the country's family structure.

In a separate decision the court decided that another law, dating from the same period and requiring divorced women to wait six months before remarrying, was in violation of the constitution.

But judges stopped short of abolishing the waiting period, saying only that a ban lasting more than 100 days was unconstitutional -- a ruling which suggested that a shorter period was acceptable.

The surname rule is a throwback to Japan's feudal family system, in which all women and children came under the control of the male head of the household.

That family system was abolished in 1948 as part of broad reforms pushed by the post-World War II US occupation, but Japan's civil code maintained the surname provision.

‘It does not violate the constitution,’ NHK quoted presiding justice Itsuro Terada as saying.

Terada noted that some people believe that changing one's surname ‘can harm individual identity’, but added that the informal use of maiden names had eased the impact.

‘Use of separate spousal names should be discussed by the legislature,’ he added, suggesting that parliamentarians could pass new legislation.

About 96 percent of women in Japan take their husband's surname.

The half-year remarriage ban, which also remained in the civil code, is linked to complex rules about the timing of a child's birth after divorce. In an era before DNA testing these were intended to determine whether a child belonged to the ex-husband or the new spouse's family.

Activists say the laws are a continued reflection of the country's male-dominated society more than a century after they came into effect, and lag behind changes in other advanced countries.

Conservatives have argued that overhauling the current system would shake the foundation of traditional families.