If the Supreme Court overturns Roe v. Wade, the legal and cultural battles over abortion that have raged for decades in the United States will increasingly be fought on a new front: abortion pills.

Medication abortion — a two-drug combination that can be taken at home or anywhere and is legal in the first 10 weeks of pregnancy — has become increasingly common, accounting for more than half of recent abortions in the United States. If the federal guarantee of abortion rights is removed, medication abortion is likely to become an even more popular method of terminating a pregnancy — and the focus of battles between states that ban abortion and those that allow it.

“Given that most abortions are early and medication abortion is harder to trace and is already kind of becoming the majority or preferred method,” said Mary Ziegler, a visiting law professor at Harvard. “It’s going to generate a lot of future legal conflicts because it’s just a way for state borders to become less relevant.”

If the justices’ decision in a Mississippi case resembles a draft opinion leaked this week that would nullify the 1973 ruling that legalized abortion, roughly half of the states are expected to quickly make all methods of abortion illegal. Other states would almost certainly continue to permit abortion, and several are already taking steps to accommodate patients from states where abortion may be prohibited.

Medication abortion is both cheaper and less invasive than surgical abortion. The Food and Drug Administration made it significantly easier to obtain it in December by removing the requirement that patients obtain the first of two pills, mifepristone, in person by visiting an authorized clinic or doctor. Patients can now consult with a doctor via video or phone, or by completing online forms, and then receive the pills by mail.

However, many conservative states have already passed legislation restricting medication abortion, such as prohibiting it before 10 weeks of pregnancy and requiring patients to visit providers in person, despite FDA rules. Telemedicine for abortion is illegal in 19 states. Americans United for Life, an anti-abortion advocacy group, ranked laws prohibiting medication abortion as the organization’s first “pressing priority” for 2022.

“In the last year, Arizona, Arkansas, Indiana, Montana, Ohio, Oklahoma, South Dakota, and Texas have enacted state-level safeguards to prevent mail-order abortion drugs, and the Tennessee Legislature recently sent such safeguards to Gov. Bill Lee,” Mallory Carroll, an official with the anti-abortion group Susan B. Anthony List, said. “In addition to creating health and safety standards, states are also increasing requirements for reporting complications from abortion drugs. We will be working with allies in additional states to tackle this growing public health threat.”

Residents of states that, if Roe were overturned, would immediately ban all abortion methods, including Texas, Missouri, Utah, and Tennessee, would be legally barred from having telemedicine abortion consultations from any location in their state, even if the doctor was located in a state where abortion is legal. Such patients would have to travel to a state where online, video, or phone consultations are legal; the IP address of the computer or phone they were using would reveal their location. The pills would then have to be mailed to them at an address in a state where abortion is legal, even if it was a post office box or a hotel.

Some patients are already doing so because they live in one of the states where telemedicine for abortion is prohibited. Some aspects of those laws are murky, such as whether patients who take the pills after returning to their home state are breaking the law in their home state.

According to reproductive health experts, if abortion were completely prohibited in those states, many more patients would travel to states where it was legal.

Several organizations, including Abortion on Demand and Hey Jane, now arrange telemedicine or online consultations and mail pills from one of two mail-order pharmacies authorized to dispense mifepristone by the two manufacturers.