As the legal battle over abortion pills winds through the federal courts, anti-abortion activists are citing a 150-year-old law, the Comstock Act of 1873, to bolster their case.

For most of the past century, that law has rarely if ever been enforced, with many of its anti-vice provisions narrowed by federal courts or considered to be vastly out of date. But with the overturning of the Roe v. Wade decision, opponents of abortion rights have begun invoking it as a legal basis for blocking the mailing of abortion medication, which could have sweeping implications for abortion access across the country.

Here is how the Comstock Act came to be and how it is being viewed today.

What does the Comstock Act say?

Among other things, the Comstock Act prohibits the mailing of “obscene, lewd, or lascivious” materials, like pornography, or any article or thing “intended for the prevention of conception or procuring of abortion.” It also prohibits shipping those things by way of express common carriers, meaning services like FedEx or UPS.

The act’s namesake, Anthony Comstock, was a deeply religious Civil War veteran turned anti-vice crusader from New York who was obsessed with combating what he saw as a culture of sexual impurity. He successfully pushed Congress to restrict materials he saw as immoral, arguing that allowing them to be distributed through the mail corrupted the public and posed a danger to children.

The Comstock Act’s definition of what was lewd material would be “radically unfamiliar” to people living today, according to Mary Ziegler, professor of law at University of California, Davis. Examples she cited included “somebody writing a letter to somebody asking them for a date if they weren’t married,” and “somebody mentioning the existence of an abortion in a newspaper.”

“The early Comstock Act enforcement is extraordinarily broad, and gets broader and broader,” Professor Ziegler said.

What effect did the law have?

The Comstock Act had a huge impact in the late 19th and early 20th centuries, according to David S. Cohen, a law professor at Drexel University.

“Thousands of people were caught up in jail and prosecuted,” Professor Cohen said. “But there was backlash, immense backlash, that really materialized in the ’20s and ’30s.”

Seismic changes in society early in the 20th century clashed with the rigidity of the Comstock Act. Women gained the right to vote in 1920, the Great Depression created an economic need for family planning, and large companies that made contraceptives began to gain more political influence. And in various rulings beginning in the 1930s, federal courts began to reinterpret the law’s meaning.

According to Professor Cohen, judges began to view the Comstock Act as banning only illegal materials from the mail, not everything deemed immoral. Their reasoning, he said, was that the old interpretation of the law went beyond what Congress originally intended.

The act’s relevance continued to fade over the next 30 years, and by the time Griswold v. Connecticut established a constitutional right to the use of contraception in 1965 and Roe v. Wade established a national right to abortion in 1973, the act was seen as a relic.

“People knew it wasn’t repealed, but it wasn’t really considered that important anymore,” Professor Ziegler said.

What brought the Comstock Act back into the spotlight?

After the Supreme Court overturned Roe v. Wade, some anti-abortion activists and lawyers began to argue that the Comstock Act made it illegal to send abortion pills by mail.

That argument is part of a high-profile abortion pill lawsuit seeking to halt the availability of mifepristone, the first pill in the two-drug medication abortion regimen — the method used in more than half of abortions in the country.

In April, U.S. District Judge Matthew Kacsmaryk, who has a history of publicly opposing abortion, issued a preliminary ruling in that lawsuit, invalidating the Food and Drug Administration’s 23-year-old approval of mifepristone. In his ruling, Judge Kacsmaryk agreed with virtually all of the plaintiffs’ arguments, including the claim that the Comstock Act makes abortion pills “nonmailable.”

An appellate court later struck part of Judge Kacsmaryk’s ruling, but affirmed major aspects of it, including that the Comstock Act would be violated “merely by knowingly making use of the mail for a prohibited abortion item.”

That reasoning contradicts a December 2022 opinion by the Justice Department’s Office of Legal Counsel, which concluded that abortion-causing drugs could be sent by mail if the sender did not intend for the recipient to use them unlawfully.

The Texas rulings were put on hold by the Supreme Court, which sent the case back to the appellate court, where a hearing will take place on Wednesday.

In a ruling this month on a motion in a separate case, a judge in West Virginia said that the Comstock Act did not apply to the mailing of a generic version of mifepristone.

What comes next?

The Texas abortion pill case may eventually be decided by the Supreme Court.

Returning to an older interpretation of the Comstock Act would have repercussions far beyond mifepristone, Professor Cohen said. The Comstock Act does not only refer to drugs, he said, but also to anything used for an abortion, which could include things like surgical gloves and medical instruments.

“Everything in a doctor’s office comes from the mail or FedEx or UPS or some version of that,” Professor Cohen said. “So if you can’t mail anything that’s used to induce an abortion, it would end abortion nationwide.”

Eliza Fawcett and Neelam Bohra contributed reporting.