The Osaka District Court ruling is the second decision on the issue, and disagrees with a ruling last year by a Sapporo court that found the ban on same-sex marriages unconstitutional. It underscores how divisive the issue remains in Japan, the only member of the Group of Seven major industrialized nations that does not recognize same-sex unions.
In its ruling, the Osaka court rejected the plaintiffs' demand for 1 million yen ($7,400) in damages per couple for discrimination they face.
The plaintiffs — two male couples and one female couple — were among 14 same-sex couples who filed lawsuits against the government in five major cities — Sapporo, Tokyo, Nagoya, Fukuoka and Osaka — in 2019 for violating rights to free union and equality.
They argued that they have been illegally discriminated against by being deprived of the same economic and legal benefits that heterosexual couples enjoy through marriage.
The Osaka court on Monday said freedom of marriage in the 1947 constitution only means male-female unions and does not include those of the same sex, and therefore banning same-sex marriages is not unconstitutional.
Judge Fumi Doi said marriage for heterosexual couples is a system established by society to protect a relationship between men and women who bear and raise children, and that ways to protect same-sex relationships are still undergoing public debate.