The American Civil Liberties Union (ACLU), the ACLU of Texas and Lambda Legal filed a lawsuit Tuesday to block the Texas Department of Family and Protective Services (DFPS) from enforcing a directive to investigate families of transgender youth and the medical professionals who treat them.

Last week Texas Governor Greg Abbott directed state health agencies to investigate the medical treatment of transgender youth as “child abuse.”

The lawsuit, which names Abbott, as well as DFPS Commissioner Jaime Masters and DFPS, as defendants, claims that these directives were issued without proper authority, in violation of the Texas Administrative Procedures Act, the separation of powers requirements of the Texas Constitution, and the constitutional rights of transgender youth and their parents.

According to the complaint:

The Governor has circumvented the will of the legislature and, in so doing, he and the Commissioner have run afoul of numerous Constitutional and statutory limits on their power. Additionally, by their actions, Defendants have trampled on the Constitutional rights of transgender children, their parents, and professionals who provide vital care to transgender children. The Defendants have, without Constitutional or statutory authority, acted to create a new definition of “child abuse” that singles out a subset of loving parents for scrutiny, investigation, and potential family separation. Their actions caused terror and anxiety among transgender youth and their families across the Lone Star State and singled out transgender youth and their families for discrimination and harassment. What is more, the Governor’s, Attorney General’s, and Commissioner’s actions threaten to endanger the health and wellbeing of transgender youth in Texas by depriving them of medically necessary care, while communicating that transgender people and their families are not welcome in Texas.

Abbott’s letter comes amid a wave of state attempts to criminalize medical care for transgender youth. Arkansas lawmakers overcame the governor’s veto to pass a bill last April banning the provision of gender-affirming care to transgender minors. That law was temporarily blocked by a federal judge in July. Similar bills have been introduced in Texas and several other states but have not yet been passed. Numerous experts have stressed that gender-affirming care is essential to the health and wellbeing of gender-diverse youth and can even save lives.