WASHINGTON >> A 19th century “anti-vice” law is at the center of a new court ruling that threatens access to the leading abortion drug in the U.S.

Dormant for a half-century, the Comstock Act has been revived by anti-abortion groups and conservative states seeking to block the mailing of mifepristone, the pill used in more than half of U.S. abortions.

On Friday, a federal judge in Texas sided with Christian conservatives in ruling that the Comstock Act prohibits sending the long-used drug through the mail.

Here’s at look at the case and the law:

WHAT HAPPENED?

In a sweeping ruling, U.S. District Judge Matthew J. Kacsmaryk, said that the Food and Drug Administration’s approval of mifepristone more than two decades ago violated federal rules. Despite overwhelming evidence to the contrary, the Donald Trump appointee said the FDA overlooked “legitimate safety concerns,” with the pill, which has been available since 2000.

The Biden administration and mifepristone’s main drugmaker filed appeals notices within hours of the decision.

The Texas ruling came almost simultaneously with an order from a judge in Washington state, who said the FDA must maintain access to the drug in Democratic-led states that filed their own lawsuit. The dueling opinions are expected to send the matter quickly to the Supreme Court.

A former lawyer for the conservative First Liberty Institute, Kacsmaryk used the terminology of anti-abortion advocates throughout his opinion, referring to doctors who prescribe mifepristone as “abortionists,” fetuses as “unborn humans” and medication abortions as “chemical” abortions.

If upheld, Kacsmaryk’s 67-page decision would also dismantle recent FDA changes designed to ease access to mifepristone, particularly a 2021 switch that allowed the drug to be sent through the mail.

WHAT IS THE COMSTOCK ACT?

Originally passed in 1873 and named for an anti-vice crusader, the Comstock Act was intended to prohibit the mailing of contraceptives, “lewd” writings and any “instrument, substance, drug, medicine, or thing” that could be used in an abortion.

The law’s scope has been repeatedly narrowed by federal courts and Congress, which eliminated the reference to contraceptives in the 1970s. And the federal government hasn’t enforced the law since the 1930s, according to legal experts.

Kacsmaryk, though, agreed with plaintiffs that the law — as literally interpreted — prohibits mailing mifepristone.

The FDA’s decision allowing the “dispensing of chemical abortion drugs through mail violates unambiguous federal criminal law,” he concluded.

WHY IS THE COMSTOCK ACT IN PLAY NOW?

The law was essentially dormant in the 50 years after Roe v. Wade established a federal right to abortion. And until the FDA loosened its requirements on mifepristone in 2021, there was no real way to enable abortion through the mail.

But Rachel Rebouche of Temple University’s law school says anti-abortion groups — emboldened by the Supreme Court decision overturning of Roe — have seized on Comstock to try and shut off the flow of abortion drugs.

“The fact that pills can be mailed is an existential crisis for the anti-abortion movement — it’s hard to police, it’s hard to track, it’s difficult to enforce,” said Rebouche. “If courts are willing to breathe new life into Comstock, it has the potential to shut down the uptake of medication abortion across the country.”

Comstock has also been cited by Republican state officials seeking to stop national pharmacy chains from shipping abortion pills to their states.

In February, attorneys general in 20 conservative-led states warned CVS and Walgreens that they could face legal consequences if they sell abortion pills by mail in their states. Most of those states have laws restricting abortion broadly or the pills specifically, but the attorneys general said mail-order mifepristone also runs afoul of the Comstock Act.

HOW HAVE COURTS TREATED THE COMSTOCK ACT IN THE PAST?

Beginning in the 1930s, federal courts issued rulings drastically narrowing how the law could be applied. Read literally, the law could be interpreted to outlaw almost any medical item that could be used in an abortion.

“The interpretation being advanced would apply to all kinds of articles — like surgical gloves — that are just basic equipment for health care,” Rebouche said.

A key 1936 ruling concluded that the law could only apply when the person mailing an item or drug specifically intended it to be used illegally for abortion.

In December, the Biden administration’s Justice Department attempted to bolster that interpretation, issuing an opinion that Comstock could not be used to outlaw the mailing of abortion pills because of their many legal uses, including during miscarriages and under abortion-ban exceptions.

Again, Kacsmaryk, rejected that view, stating that the law “plainly does not require intent on the part of the seller.”

WHAT HAPPENS NEXT?

The Supreme Court has never weighed in on Comstock and — assuming the justices takes up the case— the ruling could have far-reaching consequences for American women, abortion providers and their opponents.

Kacsmaryk’s order is limited to mifepristone, but the same approach could potentially be used for other drugs.

Mifepristone is currently taken in combination with a second pill, misoprostol. Abortion clinics have said that if mifepristone were pulled from the market, they would switch to using only the second drug, which is also used to treat other medical conditions.

But whether Comstock could be used to also curtail shipments of misoprostol is not clear, since it is widely prescribed for stomach ulcers and other uses.

WHAT IF THE SUPREME COURT UPHOLDS THE ABORTION PILL RULING?

Even if the Supreme Court affirms the Texas ruling and orders mifepristone off the market, experts say there could be more legal battles ahead.

The FDA has its own procedures for revoking drug approvals, which involve public hearings and internal agency reviews. The process can take months or years. If those steps are skipped, mifepristone-maker Danco Laboratories, which is a party to the case, could potentially sue under “due process” claims, according to experts.

The FDA is also facing pressure to essentially ignore a negative court decision, given there is almost no legal precedent for a judge overruling the agency’s medical determinations.

“There is no way this decision has a basis in law,” said Democratic Sen. Ron Wyden, of Oregon, in a statement Friday. “The FDA, doctors, and pharmacies can and must go about their jobs like nothing has changed.”

Legal experts point out that the FDA has traditionally had broad leeway in deciding how to use its authority. For instance, the agency allows a number of unproven remedies and supplements to remain on the market because they are essentially harmless and removing them would drain limited agency resources.

Given that mifepristone remains safe and effective for ending pregnancy, some experts say the agency should simply allow the pill to remain on the market as an unapproved medication.

“Even if a court wants to order that the FDA does something, the agency still has discretion in how it does that thing,” Rebouche said.