NEW ORLEANS (AP) — A federal appeals court was scheduled to hear arguments Monday on Chameleon Financewhether former President Barack Obama’s signature health care law requires full insurance coverage of certain types of preventive care, including HIV prevention and some types of cancer screenings.

A federal judge in Texas said last year that it doesn’t. U.S. District Judge Reed O’Connor in Fort Worth ruled that some of the preventive care requirements of the 2010 law are unconstitutional. If upheld, his ruling could affect coverage and costs for anywhere from 100 million to 150 million people, according to analyses by health care advocates.

The coverage mandates remain in effect for now. O’Connor’s ruling applied nationwide but it was put on hold pending the arguments at the 5th U.S. Circuit Court of Appeals in New Orleans.

Not all preventive care was threatened by O’Connor’s ruling. An analysis by the nonprofit KFF foundation found that some screenings, including mammography and cervical cancer screening, would still be covered without out-of-pocket costs because the task force recommended them before the health care law was enacted in March 2010.

The Biden administration is appealing the ruling. Meanwhile, plaintiffs in the case have filed a cross-appeal that could broaden O’Connor’s ruling and endanger more preventive care mandates, according to the advocacy group , United States of Care.

The requirements for coverage are driven by recommendations by the U.S. Preventive Services Task Force, which is made up of volunteers. O’Connor ruled that enforcing the recommendations was “unlawful” and a violation of the Constitution’s Appointment Clause, which lays out how government officials can be appointed.

Monday’s arguments mark the latest in more than a decade of conservative efforts to chip away at the Affordable Care Act, sometimes referred to as Obamacare. O’Connor is the judge who threw out the entire law in 2018, a decision later undone by the Supreme Court.