A judge in Texas has heard arguments in a lawsuit filed by anti-abortion groups that seeks to ban an abortion pill used widely across the United States in the latest legal battle over reproductive health care in the country.

US federal Judge Matthew Kacsmaryk, a conservative appointee of former President Donald Trump, has yet to issue a ruling after more than four hours of argument over whether to ban mifepristone, an abortion pill approved by the Food and Drug Administration more than 20 years ago.

The Alliance for Defending Freedom and other groups asked Kacsmaryk on Wednesday for an immediate order that would revoke or suspend the drug’s approval.

Such a step would be an unprecedented challenge to the FDA, which in 2000 approved mifepristone in combination with a second pill as a safe and effective method for abortions.

It would also further reshape the landscape of reproductive rights in the US after a decision by the nation’s top court in June to overturn its landmark 1973 abortion rights ruling, Roe v Wade.

Abortion pills are the most common form of abortion in the US, accounting for more than half of all procedures since 2020, according to the Guttmacher Institute, an abortion rights research organisation.

“If Judge Kacsmaryck rules to revoke the FDA’s approval of mifepristone, it won’t be based in science or evidence,” the abortion rights group NARAL wrote on Twitter ahead of Wednesday’s hearing. “It will be based in anti-choice ideology.”

In June, the anti-abortion rights movement celebrated when the conservative-majority US Supreme Court ruled 6-3 to strike down Roe v Wade.

In the months since, numerous Republican-governed states have instituted severe restrictions or outright bans on abortion, and anti-abortion campaigners have shifted their focus to trying to ban abortion pills as well.

Mifepristone is the first of two pills taken to induce an abortion. The pill stops a pregnancy from proceeding, and a second pill taken up to 48 hours later, misoprostol, causes cramps, bleeding and the emptying of the uterus.

The process can be completed safely at home and is approved for up to 10 weeks of pregnancy.

The Texas lawsuit alleges that the FDA’s approval of mifepristone in 2000 was flawed for several reasons, including an inadequate review of the pill’s safety risks.

The suit also challenges several later FDA decisions that loosened restrictions on the pill, including eliminating a requirement that women pick it up in person.

But abortion rights advocates have slammed the lawsuit as another attack on reproductive justice in the US.

A small group of protesters demonstrated on Wednesday outside the courthouse in Amarillo, Texas, where the case is being heard. They carried signs bearing slogans such as, “Not your uterus, not your decision” and “Defend medication abortion.”

Lindsay London, a 41-year-old nurse, said the case was “100 percent ideologically based”.

“If they were concerned about people’s health, there would be many other actions they would be taking,” London told the AFP news agency. “It’s ideological, not based in science.”

Major medical organisations, including the American College of Obstetricians and Gynecologists, have weighed in on the side of the FDA, saying mifepristone “has been thoroughly studied and is conclusively safe”.

Legal experts also say there is little precedent for a lone judge overruling the scientific assessment of the FDA, which stated in a January filing that halting the sale of mifepristone would “dramatically” harm the public interest and push women to undergo unnecessary surgical abortions.

It is not clear when Kacsmaryk will make his decision, but if he rules in favour of the plaintiffs, the US government is widely expected to appeal.

If he rules against the FDA, it also remains unclear how quickly access to mifepristone could be curtailed or how the process would work. The FDA has its own procedures for revoking drug approvals, which involve public hearings and scientific deliberations and can take months or years.

aljazeera