A fragile truce between the states on abortion just collapsed: Last week, Texas Attorney General Ken Paxton filed a lawsuit against a doctor in New York for mailing pills into the state. The physician, Margaret Daly Carpenter, is part of a group called the Abortion Coalition for Telemedicine, which represents doctors who mail abortion medications — in this case, mifepristone and misoprostol — to states where the procedure is banned. ACT refers to these clients as “shield providers” because they rely on the protections afforded by so-called shield laws, which are on the books in 23 states and the District of Columbia to protect providers and other possible defendants from out-of-state legal consequences. Texas’ suit is the first to challenge these shield laws, and it’s likely to raise unprecedented legal questions in the new year.
The genesis of shield laws dates from shortly before the Supreme Court overturned Roe v. Wade, after Missouri considered (but ultimately didn’t pass) a bill that would project its abortion ban outside state lines. That inspired a pre-emptive strike from lawyers supportive of abortion rights, who drafted shield laws to prevent criminal and civil consequences for residents who helped out-of-state abortion-seekers.
With this lawsuit, we enter uncharted territory.
The most ambitious — and most consequential — form of assistance involved doctors in jurisdictions where abortion is protected mailing abortion pills into states where abortion is banned. This strategy has had obvious practical advantages: It makes medication available to patients who live in remote areas or lack the resources to easily travel out of state. The shield network also makes pills available far more quickly than would be the case if doctors were based offshore. Shield doctors can organize in a range of states to mail tens of thousands of pills into states where abortion is a crime. And there has been no challenge to shield provisions in federal court — until now.
With this lawsuit, we enter uncharted territory. Texas has accused Carpenter of practicing medicine without a license and violating a state law limiting the availability of abortion pills, with civil penalties for the latter starting at $100,000. If Texas’ lawsuit goes forward, it seems likely, Texas will win in its own state courts. A Texas court will have to decide which state’s law applies, given that the physician was based in one state and the patient and the abortion in another. Standard telehealth law tends to focus on the location of the patient. And Texas will argue that it has the right to apply its laws because of where the abortion — the injury in Texas’ view — took place. That means Texas could win a civil judgment against Carpenter even if she never travels to the state.
The real question might be whether New York will enforce a judgment against Carpenter despite what its shield law and state constitution say about reproductive rights. Texas will argue that New York has no choice because of the Full Faith and Credit Clause, which generally requires states to honor valid, final judgments and decisions of other states. But the clause has exceptions. For example, states don’t have to carry out the penal policies of other states — a term that encompasses not just criminal laws but other laws that have the purpose of punishing “an offense against the public justice of the state.” While state courts have rarely applied this exception, Texas’ laws — especially civil penalties on abortion pills — look pretty penal: Their goal is not to help an injured patient but to enforce Texas’ concept of justice. New York courts may simply refuse to honor whatever ruling a Texas court reaches. Would Texas then try to garnish money from accounts in banks with in-state branches? Could Carpenter easily frustrate that ambition by moving her assets to a different bank?
The answers to these questions are that no one knows.
Further complicating matters is the fact that Carpenter could sue Texas right back under New York’s shield law, which authorizes so-called clawback lawsuits against anyone who brings a suit that counts as “unlawful interference with protected rights.” If she does, the state will argue it has sovereign immunity from any lawsuit that Carpenter brings under the 11th Amendment, which limits when states can be sued in federal court. And Texas will say it definitely has the power to go after Carpenter because she chose to have contact with the state when she mailed pills to patients within its borders.
What is certain is that the Supreme Court will ultimately have to decide these legal questions. Many of them land in enough of a legal gray area that predicting the outcome with any certainty is challenging, especially with conservative judges who are likely to sympathize with Texas’ view of reproductive rights. These lawsuits will tee up even messier questions. Here’s another certainty: Whatever happens in this case will be just the tip of the iceberg. If Texas and other anti-abortion jurisdictions can target doctors who mail pills into their states, it will be harder to target providers who serve out-of-state patients who travel to places where abortion is legal. And then there are in-between scenarios — for example, if a patient receives a pill in one state and ingests it another. None of that even touches on whether states like Texas can go after someone for providing information that facilitates abortion travel or a corporation for subsidizing abortion-related travel of employees in ban states. And though Texas can claim sovereign immunity, that won’t be true of other plaintiffs, like the former partners of abortion patients, who can also bring suit against out-of-state defendants. These lawsuits will tee up even messier questions. States may even race to be the first to reach a final judgment they can then push their neighbors to recognize. In concurring with the overturning of Roe v. Wade, Justice Brett Kavanaugh quoted Justice Antonin Scalia’s complaint that “Roe fanned into life an issue that has inflamed our national politics in general.” The man who appointed Kavanaugh to the court agreed: With Roe gone, Donald Trump said, “we have abortion where everyone wanted it from a legal standpoint.” It will soon be quaint to think of the demise of Roe as Trump and the conservative justices do: as a kind of settlement that would simplify and de-escalate conflicts about abortion. Texas’ lawsuit makes it clear that with Roe gone, things are about to get much more complicated — and much worse.
Mary Ziegler is a law professor at the University of California, Davis, School of Law and the author of "Roe: The History of a National Obsession." 
