A federal judge in Texas who previously ruled to dismantle the Affordable Care Act struck down a narrower but key part of the nation�s health law Thursday in a decision that opponents say could jeopardize preventive screenings for millions of Americans.

The ruling by U.S. District Judge Reed O�Connor comes more than four years after he ruled that the health care law, sometimes called �Obamacare,� was unconstitutional. The U.S. Supreme Court later overturned that decision.

His latest ruling is likely to start another lengthy court battle: O�Connor blocked the requirement that most insurers cover some preventive care such as cancer screenings, siding with plaintiffs who include a conservative activist in Texas and a Christian dentist who opposed mandatory coverage for contraception and an HIV prevention treatment on religious grounds.

O�Connor wrote in his opinion that recommendations for preventive care by the U.S. Preventive Services Task Force were �unlawful.�

The Biden administration had told the court that the outcome of the case �could create extraordinary upheaval in the United States� public health system.� It is likely to appeal.

The U.S. Department of Health and Human Services did not immediately respond to a message seeking comment on the ruling.

In September, O�Connor ruled that required coverage of the HIV prevention treatment known as PrEP, which is a pill taken daily to prevent infection, violated the plaintiffs� religious beliefs. That decision also undercut the broader system that determines which preventive drugs are covered in the U.S., ruling that a federal task force that recommends coverage of preventive treatments is unconstitutional.

Employers� religious objections have been a sticking point in past challenges to former President Barack Obama�s health care law, including over contraception.

The Biden administration and more than 20 states, mostly controlled by Democrats, had urged O�Connor against a sweeping ruling that would do away with the preventive care coverage requirement entirely.

�Over the last decade, millions of Americans have relied on the preventive services provisions to obtain no-cost preventive care, improving not only their own health and welfare, but public health outcomes more broadly,� the states argued in a court filing.

The lawsuit is among the attempts by conservatives to chip away at the Affordable Care Act � or wipe it out entirely � since it was signed into law in 2010. The attorney who filed the suit was an architect of the Texas abortion law that was the nation�s strictest before the Supreme Court overturned Roe v. Wade in June and allowed states to ban the procedure.

(AP)