The dueling arguments are part of an escalating federal court battle in Texas over a lawsuit filed by anti-abortion physicians last November, which seeks to overturn the FDA’s more than two-decade-old approval of mifepristone.

Used in combination with misoprostol, mifepristone is the most common method to terminate a pregnancy in the U.S., accounting for about half of all abortions.

The abortion rights group NARAL Pro-Choice America, in an analysis published Friday, said 40 million women would lose access to the abortion pill if the court overturns the FDA’s approval.