Missouri enacted SB39 barring transgender students from K-12 and college sports by birth-certificate sex

On June 7, 2023, Missouri Gov. Mike Parson signed Senate Bill 39 in Jefferson City, enacting Senate Substitute No. 2 for SB 39 and adding Section 163.048 to Chapter 163 of the Revised Statutes of Missouri. The law bars any student from competing in an athletics competition designated for the biological sex opposite to the student's biological sex "as correctly stated on the student's official birth certificate," defining sex as the categories of male and female based on reproductive biology at birth. It reaches private schools, public school districts, public charter schools, and public or private institutions of postsecondary education alike, with a narrow exception permitting a student assigned female to compete in a male-designated competition where no corresponding female competition exists.

The enrolled act was passed by the 102nd General Assembly and enforces the ban through funding: any covered school or institution that violates it "shall not receive any state aid under this chapter or chapter 173 or any other revenues from the state." Parson, who signed SB 39 the same day as Senate Bill 49's ban on gender-affirming care for minors, defended the pair as an effort to "protect the integrity of female sports." By keying athletic eligibility to birth-certificate sex, the law effectively excludes transgender students from playing on teams matching their gender identity across Missouri's public and private education systems.

Section 163.048 took effect August 28, 2023, and by its own terms expires August 28, 2027. The statute also creates a private cause of action for students deprived of an athletic opportunity by a violation and directs the state education departments to promulgate implementing rules.