Japan's highest court has declared that a legal provision mandating sterilisation surgery for individuals seeking a legal gender change is unconstitutional, as reported by media outlets.

International entities, including the European Court of Human Rights. the World Professional Association for Transgender Health and UN experts, have criticised this requirement as discriminatory and that it infringed upon human rights.

However, some Japanese lawmakers and women's rights groups said a ruling that challenges the law would create confusion and undermine women's rights. Japan's Supreme Court had rejected a similar case in 2019.

The Human Rights Watch welcomed the ruling and said the government must now follow up.

"The government is under the obligation to make any laws constitutional, so the government now needs to act quickly to remove the clause," said Kanae Doi, Japan director of the HRW. "It's late, but never too late."

The case was initiated by a transgender woman under 50 years of age, challenging conditions that violate constitutional rights.

While the decision has been welcomed by human rights advocates, it has stirred controversy in Japan, where some argue that it might undermine women's rights.

The ruling calls for a reassessment of the existing legal framework.

Japanese law states that people who want to change gender must present a diagnosis of gender dysphoria and meet five requirements.

Those requirements are at least 18 years of age; being unmarried; not having underage children; having genital organs that resemble those of the opposite gender; and having no reproductive glands or ones that have permanently lost their function.