Japan's Supreme Court on Wednesday declared in a historic ruling that a law requiring surgery to remove a person's reproductive capabilities to register a gender change was unconstitutional in a case brought by a transgender woman.

The judgment, which was a consensus of all 15 justices of the top court's Grand Bench, marked a turnaround from a 2019 top court decision that had found a legal provision requiring sterilization for a gender change on a family registry constitutional.

People "are forced to make a tough choice between surgery and abandoning the decision to change genders," the top court said, citing progress in medical knowledge since the law for people with gender dysphoria came into force in 2004 and an increasing trend overseas against required sterilization.

The latest development will lead the government to review the sterilization requirement, opening up the possibility of transgender people officially changing their gender without removing ovaries or testicles.

Photo taken on Oct. 25, 2023, shows the Supreme Court in Tokyo. (Kyodo) 

But the top court's Grand Bench stopped short of reaching a conclusion on another surgery requirement that focuses on the physical appearance of the genitals. It mandates that they closely match the gender the individual seeks to change to, and the top court has requested a high court to reevaluate this particular requirement.

The applicant in the case, who was born as a man but identifies as a woman, said the outcome was "not as hoped."

"I am very disappointed that my gender change will not be realized at this moment," the woman, who lives in western Japan and has only disclosed her age as younger than 50, said in a statement conveyed through her lawyers.

She has been hoping to change her legal gender without surgery, asserting that her reproductive capabilities have declined following years of hormone therapy.

The surgery requirement "causes an extreme physical and economic burden" and therefore violates the Constitution, which guarantees respect for individuals and equality under the law, she has argued.

The woman's request for a gender change has been denied by a family court and high court due to her not undergoing surgery.

The top court, however, acknowledged Wednesday that required sterilization is a restriction violating the Constitution's Article 13, which guarantees individuals' freedom from "invasion into their body against their will."

The Japanese law on gender dysphoria stipulates five conditions for those wishing to register as a member of the opposite sex, in addition to a diagnosis of gender dysphoria from at least two physicians.

The five conditions comprise being no less than 18 years old, unmarried, having no underage children, having "no reproductive glands or whose reproductive glands have permanently lost function," and having "a body that appears to have parts that resemble the genital organs of those of the opposite gender."

The top court explained that the sterilization requirement was believed to have been established to prevent "confusion and drastic societal changes," such as instances where a child is born via the reproductive function associated with the individual's original gender.

However, it concluded that it would be "extremely rare" for problems to occur even without the requirement. It noted that legal issues on child-parent relationships can be solved through legislation.

From a medical standpoint, sex-reassignment surgery was previously seen as the final stage in a series of treatments, but currently, such a phased treatment approach is no longer taken, it said.

The top court also pointed to a "greater understanding regarding gender dysphoria" in the public, with more than 10,000 people having successfully changed genders on the family registry over the past 19 years.

In 2019, the top court's Second Petty Bench found the sterilization requirement "currently constitutional" in a case involving a transgender man but also called for a "continuous" examination of the issue in accordance with societal changes.

Earlier this month, the Hamamatsu branch of the Shizuoka Family Court ruled the sterilization requirement unconstitutional, allowing a transgender man who brought the case to court to be listed as male without surgery. It was the first such judicial judgment in Japan, according to lawyers.

Discussions over the necessity for surgery have been increasing in Japan, with many countries worldwide already deeming surgery unnecessary in order to switch genders.

Yasuhiko Watanabe, a professor at Kyoto Sangyo University, said Japan's law was in line with global standards when it first went into force, but it has since "fallen behind" as countries revised their own requirements.

About 40 out of approximately 50 countries that have laws on gender change do not require the loss of reproductive capabilities, the Hamamatsu branch said when it issued its decision.

Sweden and the Netherlands abolished the sterilization requirement in 2013, while Spain and Britain never mandated it when they put in place laws in the 2000s.

But even if the sterilization requirement is abolished in Japan, the physical appearance condition could still weigh on transgender people seeking official gender change.

There are cases in which female-to-male hormone therapy could lead to physical changes that alter the appearance of genitals, but male-to-female therapy may not produce similar results and could still require surgery in order to fulfill the requirements, pundits say.

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