By Jessica Mathews & Jon King /

A local lawmaker has introduced legislation she says aims to protect female sports, while opponents maintain it is unconstitutional and discriminates against transgender high school athletes.

Republican State Senator Lana Theis of Brighton Township introduced Senate Bill 218 Wednesday. It would require Michigan schools to only permit students of the same assigned biological sex to compete against one another in school-sanctioned gender-specific athletics. Theis said her bill will ensure that in school sports, student-athletes will compete against one another according to their biological sex — females against females, and males against males.

The bill would require that Michigan school districts establish and maintain policies to that effect. The bill defines biological sex as “the physical condition of being male or female as determined by an individual’s chromosomes and anatomy as identified at birth.”

In a press release, Theis said something must be done to preserve the legacy of Title IX to ensure that girls and women have an equal opportunity to compete in athletics on a level playing field. “Sadly, today, identity politics threatens all that was sacrificed and gained, " said Theis. "Across our country, biological females are losing opportunities at titles, records, scholarships and, at times, participation itself."

The Detroit Free Press reports that Theis did not cite any examples of opportunities lost in her statement, and did not respond to questions sent to a Senate spokesman.

Equality Michigan, an LGBTQ anti-violence and political advocacy organization, is among the groups opposing the legislation. It says the bill represents a misguided and mean-spirited attack on some of the most vulnerable youth in the state and it only adds to the stigma that transgender students face. Officials say local schools across the nation are already creating policies that protect transgender youth and ensure a level playing field for all students. The group says blanket bans on transgender student-athletes undermines progress and similar laws have already been struck down by federal courts as unconstitutional.

Theis' bill follows an executive order signed by President Joe Biden referencing a recent Supreme Court decision in arguing any discrimination based on gender and sex is wrong. The order, signed just a few days into his administration, states, "Every person should be treated with respect and dignity and should be able to live without fear, no matter who they are or whom they love. Children should be able to learn without worrying about whether they will be denied access to the restroom, the locker room, or school sports."

The order points to a 6-3 opinion of the high court last year in which it determined it was unconstitutional to fire someone solely due to the fact that person is gay or transgender.

The bill was introduced the same day that more than 500 college athletes signed a letter to the NCAA Board of Governors asking the organization to refuse to schedule championships in states that have banned transgender participation in sports. The move follows a wave of legislative efforts across the country aimed at transgender athletes. The letter to the NCAA asks the board to uphold the organization’s nondiscrimination policy, citing the decision to move championships out of North Carolina in 2016 in response to legislation targeting transgender use of public restrooms.

Senate Bill 218 has been referred to the Senate Committee on Education and Career Readiness for consideration.