In a landmark ruling, Japan's Supreme Court has decided that requiring people to undergo surgery to remove their reproductive functions when they wish to officially change gender is unconstitutional.

A person who was recorded as male at birth but now identifies as a woman asked a family court to allow a gender change without surgery, claiming that enforcing it would violate their human rights and the Constitution.

Both the family court and then a high court dismissed the case. But the Grand Bench of the Supreme Court said on Wednesday that the requirement does indeed violate the Constitution. The top court has ordered a high court to retry the case.

Under current Japanese law, a person's gender on official documents can only be changed if certain conditions are met, such as the individual no longer having the reproductive functions he or she was born with. That effectively requires the person to undergo surgery.

This is the twelfth time since the end of World War Two that a law provision has been judged unconstitutional. The Diet will be forced to review the law.

An international organization that surveys LGBTQ communities says Japan is one of 18 countries that require surgery for a gender change, a position opposed by the World Health Organization.

At least 17 nations, including Argentina and Denmark, allow transgender people to self-identify their gender.