A Twitter storm was created after a photo of an affidavit was shared online
Some public schools in Oklahoma have demanded that parents sign what have been described as "biological sex affidavits" if they want their children to compete in school sports.
March saw Oklahoma Governor Kevin Stitt sign a bill that banned transgender athletes from competing in teams and categories related to their gender identity and not the sex they were assigned at birth.
As communicated by a photo shared on Twitter, some bodies such as Woodall Public Schools have already begun issuing an affidavit which forms part of their athletics policy for the 2022-2023 school year.
The address on the document lines up with that of Woodall Elementary School which is around an hour southeast of the state's second-largest city Tulsa in Tahlequah.
To NBC News, Woodall Public Schools' superintendent Ginger Knight confirmed that their district is required by Oklahoma state law to have students and their parents complete the form and attest what the child's sex was at birth should they wish to take part in sports.
A photo of the affidavit went viral on Twitter when shared by Erin Matson, who is abortion rights group Reprocation's executive director.
"This has nothing to do with encouraging girls to be athletes," Matson claimed. "This is totalitarianism. It is the white nationalist agenda. The anti-LGBTQ agenda. The anti-abortion agenda. It is all the same agenda."
Oklahoma was the US' 13th state to introduce such a bill and was followed by five others to make a total of 18.
Though almost all of those states have decided sports teams should be determined by the sex of their members that was assigned at birth, Oklahoma is the only one thus far known to require an affidavit that swears a student's assigned sex.
The changes come at a time when trans participation is one of the most discussed topics in sport amid the successes of figures such as ex-UPenn swimmer Lia Thomas.
Previously competing on the Ivy League college's men's team, Thomas then smashed a number of records on its female counterpart after transitioning but could have her dream to compete at the Paris 2024 Olympics scuppered thanks to recent amendments made by world governing body Fina.
Fina has banned all trans athletes who have taken any part in male puberty and has also vowed to create a new 'open' category which British Triathlon will introduce next year.
In the US, the Education Department issued guidance in 2021 that said it would interpret a federal law known as Title IX that protects students from suffering sex-based discrimination in federally funded public schools.
But the administration of US president Joe Biden's Title IX directive is on hold at the moment after a Tennessee federal judge blocked it in July.
The judge did this as imposing the law would make it impossible for some US states to introduce and enforce their own laws on trans participation in sport and the use of public restrooms.