Donald Trump is speaking out of both sides of his mouth on abortion.

On the one hand, Trump frequently claims credit for the Supreme Court’s decision eliminating the constitutional right to an abortion — and well he should, since the three Republicans he appointed to the Supreme Court all joined the Court’s 2022 decision permitting abortion bans. As Trump told Fox News last summer, “I did something that no one thought was possible. I got rid of Roe v. Wade.”

At the same time, Trump at least claims that he has no interest in signing new federal legislation banning abortion. When a reporter asked Trump if he would sign such a ban last month, Trump’s answer was an explicit “no.”

Behind the scenes, however, many of Trump’s closest allies tout a plan to ban abortion in all 50 states that doesn’t require any new federal legislation whatsoever. The linchpin of this plan is the Comstock Act, a long-defunct, 1873 law that, among other things, purports to ban “any drug, medicine, article, or thing designed, adapted, or intended for producing abortion” from being mailed or otherwise transported by an “express company” such as UPS or FedEx.

Anyone who violates this law faces up to five years in prison — and the maximum sentence doubles for repeat offenders. Thus, anyone who delivers an abortion medication, or any device used in a surgical abortion, could potentially face such extraordinary sanctions that the transit of such goods would shut down.

Many of the leading proponents of using Comstock to ban all abortions, moreover, are likely to be very influential within a second Trump administration, if such a thing occurs. The Heritage Foundation’s Project 2025, for example, touts enforcing Comstock to ban abortion medication in its 920-page mega-white paper outlining policies for Trump.

Still, these precedents are only meaningful if the Supreme Court chooses to follow them, and betting on the same justices who overruled Roe to honor previous pro-abortion decisions is always a dangerous bet. It will get even more dangerous if Trump gets to appoint more justices.

And, even if the Court ultimately decided to follow past decisions reading Comstock narrowly, months or years would likely pass between the Trump Justice Department’s decision to file criminal charges under the Comstock Act, and a Supreme Court decision halting that prosecution. In the interim, few, if any, distributors of medications and medical supplies are likely to risk shipping anything that could lead to themselves being prosecuted.

So, while there is a fair amount of uncertainty about whether a second Trump administration could permanently shut down all legal abortions in the United States by enforcing the Comstock Act, it is likely that, at the very least, a Trump Justice Department could shut down abortion care for months or even years while the courts were sorting out what to do with Comstock prosecutions.

Similarly, the law imposes a strict censorship code, targeting any “writing” that can be used “for any indecent or immoral purpose” — a provision that violates any plausible understanding of the First Amendment right to free speech.

The Comstock Act’s namesake is Anthony Comstock, a 19th-century anti-vice crusader who wielded it and similar state laws against artists, authors, and reproductive health providers as indiscriminately as he wielded it against actual pornographers. Comstock once successfully brought criminal charges against an art gallery owner for selling reproductions of famous nude paintings. He also bragged, after a woman he arrested for selling contraceptive pills died by suicide, that she was the 15th person targeted by one of his investigations to take her own life.

The censorious values that produced the Comstock Act, in other words, are quite alien to most modern-day Americans. The law stems from an era when women could not vote, when reproductive health care was far cruder and less reliable than it is today, and when Congress thought it was a good idea to ban books and fine art.

A 2022 memo by the Justice Department’s Office of Legal Counsel lays out the very strong case for reading the Comstock Act narrowly. This memo argues that the law does not prohibit mailing or otherwise transporting abortion medications “where the sender lacks the intent that the recipient of the drugs will use them unlawfully.”

Thus, under the current Justice Department’s reading of the law, abortion-related materials may still be shipped to states where abortion is legal. They may also be shipped if the sender is unaware that the recipient intends to use the item for an illegal purpose.

As the memo notes, federal appeals courts have held for more than a century that the Comstock Act should not be read as a general ban on shipping any abortion-related item. In Bours v. United States (1915), for example, the United States Court of Appeals for the Seventh Circuit held that the law must be given a “reasonable construction” to permit physicians to advertise in the mail that they will perform a lifesaving abortion.

Later decisions read the law even more narrowly. One of the seminal court decisions interpreting the Comstock Act, the hilariously named Second Circuit decision in United States v. One Package of Japanese Pessaries (1936), held that the law only applies when someone ships an item intending it to be used for an illegal purpose.

The Comstock Act, One Package concluded, “was not to prevent the importation, sale, or carriage by mail of things which might intelligently be employed by conscientious and competent physicians for the purpose of saving life or promoting the well being of their patients.” Accordingly, the court ruled that the statute must only be read to target “unlawful” activity.

Though the Supreme Court never explicitly embraced the reasoning of Bours or One Package, that’s most likely because the Court’s constitutional decisions rendered the Comstock Act irrelevant for many decades. The Court’s decisions in Griswold v. Connecticut (1965) and Eisenstadt v. Baird (1972) established a constitutional right to contraception, thus preventing Comstock from being used to target birth control. And Roe, of course, until very recently prevented the government from banning abortion.

Nevertheless, there are powerful legal arguments supporting the proposition that cases like One Package remain good law today and should prevent nearly any prosecution under the Comstock Act. As the Justice Department notes in its memo, the Postal Service “accepted the courts’ narrowing construction of the Act in administrative rulings, and it informed Congress of the agency’s acceptance of that construction” when Congress amended the law after Griswold to largely remove its provisions targeting contraception.

Ordinarily, when Congress amends a law that has been consistently interpreted in a particular way by the courts, Congress is understood to ratify the courts’ reading of that law. As the Supreme Court held in Texas Department of Housing and Community Affairs v. Inclusive Communities Project (2015), “if a word or phrase has been ... given a uniform interpretation by inferior courts ... a later version of that act perpetuating the wording is presumed to carry forward that interpretation.”

Many states, meanwhile, apply a doctrine known as “desuetude” to criminal laws that remain on the books, but that haven’t actually been used for a very long time. As the West Virginia Supreme Court said in a 1992 opinion, “a law prohibiting some act that has not given rise to a real prosecution in 20 years is unfair to the one person selectively prosecuted under it.”

That said, this same West Virginia opinion also warned that the desuetude doctrine does not encompass particularly reprehensible acts — “if no one had been prosecuted under an obscure statute prohibiting ax murders since Lizzie Borden was acquitted, we would still allow prosecution under that statute today” — so even if the US Supreme Court were inclined to embrace this doctrine, the Republican-controlled Court might look upon abortion as morally similar to murder.

Ultimately, in other words, the fate of a Comstock prosecution is not likely to rest upon whether Congress ratified One Package, or on whether there is legal support for the proposition that long-defunct criminal laws cease to function. The Supreme Court is made up of political appointees, some of whom are quite willing to ignore the law to achieve partisan goals, and the only way to definitely shut down Comstock prosecutions is to convince a majority of the justices to do so.

Many Republican judges, meanwhile, have been quite willing to revive long-dead abortion bans now that Roe is no longer around. Just last month, for example, Arizona’s Supreme Court reinstated a Civil War era ban on abortions — although the state legislature quickly moved to repeal that ban.

All of which is a long way of saying that the current status of the Comstock Act is highly uncertain, and will depend on who sits on the Supreme Court if and when the Justice Department decides to bring a prosecution under this law. And, even in the best-case scenario, if a future Justice Department is willing to do so, the mere threat of a Comstock prosecution is likely to shut down access to abortion pills (and potentially to surgical equipment used to perform abortions) throughout the country.