A lesbian woman who donated an egg to her partner has been granted parental rights to her genetic child by the Florida Supreme Court.

She was not granted the rights by virtue of being the natural mother but simply because she intended to be the mother.

The natural tie was given no weight by the court and therefore does not create new rights for egg and sperm donors as such.

It ordered a lower court to work out custody, child support and visitation arrangements.

The case involves two women, identified only by their initials, who had a child together. One donated an egg that was fertilised and implanted in the other, who gave birth in 2004.

But two years later the couple split up, and the birth mother took the girl and left the country.

The other woman, who is the biological mother, used a private detective to find her former partner in Australia, and a custody fight ensued.

The birth mother tried to use a Florida law that prevents sperm or egg donors from claiming parental rights to children born to other couples.

Her lawyer also cited a standard form donors are required to sign relinquishing parental rights. The court rejected both arguments, saying the law doesn’t apply in this case because the couple clearly planned to parent the child together.

The court wrote that the case didn’t have to be an “all-or-nothing decision.”

“The couple’s actions before and after the child’s birth — including their use of funds from their joint bank account, their statements to the reproductive doctor that they intended to raise the child as a couple, the counseling they underwent to prepare themselves for parenthood, the use of a hyphenated last name for the child, and the joint birth announcement — reveal that the couple’s agreement in actuality was to both parent the child,” the court wrote.

However, the ruling does not override the Florida law and it can still be applied in cases where anonymous donors provide sperm or eggs to couples.

“If you were a sperm donor, would this help you get parental rights? No, it wouldn’t,” said Elizabeth Schwartz, a Miami Beach attorney who specialises in family law and who advocates for gay and lesbian issues.

“They really looked at what was intended … The law wasn’t thrown out, it was just thoughtfully applied.”

The biological mother cried when she heard the news, said lawyer Robert Segal, who represents the woman. She has not seen her daughter in six years. The girl will be 10 in January and now is in Florida, but the birth mother has not been cooperative in providing details about her life, Segal said.

“The case represents a recognition of the fundamental right a parent has to parent their child, regardless of that parent’s sexual orientation or the manner by which the child is conceived,” said Christopher Carlyle, a lawyer who assisted on the biological mother’s appeal.