LGBT groups on Monday filed a lawsuit challenging a Department of Health and Human Services (HHS) rule change that eliminates transgender protections in the Affordable Care Act, also known as Obamacare.

HHS's rule, finalized earlier this month, reverses an Obama-era regulation that expanded the definition of sex as it relates to discrimination in health care to include gender identity. HHS's new rule defines sex as “determined by biology.” It is expected to take effect on August 18, 2020. (It should be noted that the underlying law prohibiting discrimination has not changed; only HHS's interpretation has changed.)

The rule was released just days before the Supreme Court ruled that gay and transgender workers are protected until existing federal civil rights law. The high court said that the term sex includes sexual orientation and gender identity.

The Trump administration has said that it would not revise the rule in light of the court's decision.

Leading the challenge is LGBT legal group Lambda Legal, which said in a statement that the administration was using HHS as a “weapon” against the LGBT community and promised to “fight back.”

“While HHS’s health care discrimination rule cannot change the law, it creates chaos and confusion where there was once clarity about the right of everyone in our communities, and specifically transgender people, to receive health care free of discrimination,” Omar Gonzalez-Pagan, senior attorney and health care strategist at Lambda Legal, said in a statement. “Today, Lambda Legal, a broad coalition of LGBTQ groups, and the people our clients serve say ‘enough’ to the incessant attacks from the very agency charged with protecting their health and well-being. For years, the Trump administration has utilized HHS as a weapon to target and hurt vulnerable communities who already experience alarming rates of discrimination when seeking care, even now, during a global pandemic. Their actions are wrong, callous, immoral and legally indefensible. We will fight back.”

In a lawsuit filed in March, Lambda Legal claimed that the Trump administration had failed to enforce LGBT nondiscrimination protections in HHS-funded programs.