Oklahoma Republican governor Kevin Stitt Wednesday signed into law a bill that bans transgender women and girls from competing on sports teams consistent with their gender at public schools and colleges in the state.

SB2, also known as the Save Women’s Sports Act, requires sports teams at public schools to be designated based on biological sex, either male, men, or boys, or female, women, or girls. It also provides a third category of coed or mixed teams. The act states that teams designated for females, women, or girls “shall not be open to students of the male sex.” Violations of the act would open up schools to lawsuits from students.

At the signing, the governor called the act “common sense,” asserting that “When it comes to sports and athletics, girls should compete against girls. Boys should compete against boys.” He stressed the biological differences between men and women and contended that it is not fair for a female athlete to compete against “a biological male.”

Tamya Cox-Touré, executive director of the ACLU of Oklahoma, said after the signing that the governor “has sent a clear message to Oklahoma’s vulnerable transgender youth that they are not welcome or accepted in our State.” She called the act an attack on the transgender community, and stated that it “violates the United States Constitution and federal civil rights law, puts Oklahoma at risk of losing federal funding, and harms transgender youth.”

The act took effect immediately after signing.