If the Supreme Court overturns Roe v. Wade, the legal and culture wars over abortion that have consumed the United States for decades would increasingly shift to a new front: the use of abortion pills.

Medication abortion — a two-drug combination that can be taken at home or in any location and is authorized for use in the first 10 weeks of pregnancy — has become more and more prevalent and now accounts for more than half of recent abortions in the United States. If the federal guarantee of abortion rights disappears, medication abortion would likely become an even more sought-after method for terminating a pregnancy — and the focus of battles between states that ban abortion and those that continue to allow it.

“Given that most abortions are early and medication abortion is harder to traceand already kind of becoming the majority or preferred method, it’s going to be a big deal,” said Mary Ziegler, a legal scholar who has written widely on abortion. “It’s going to generate a lot of forthcoming legal conflicts because it’s just going to be a way that state borders are going to become less relevant.”

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

Medication abortion is less expensive and less invasive than surgical abortions. In December, the Food and Drug Administration made access to it significantly easier by lifting the requirement that patients obtain the first of the two pills, mifepristone, by visiting an authorized clinic or doctor in person. Now, patients can have a consultation with a physician via video or phone or by filling out online forms, and then receive the pills by mail.

But many conservative states have already begun passing laws to restrict medication abortion, including banning it earlier than 10 weeks’ gestation and requiring patients to visit providers in person despite FDA rules. Nineteen states ban the use of telemedicine for abortion. This year, Americans United for Life, an anti-abortion advocacy group, listed laws against medication abortion as first among the organization’s “pressing priorities” for 2022.

“In the last year, Arizona, Arkansas, Indiana, Montana, Ohio, Oklahoma, South Dakota and Texas have enacted state-level safeguards to stop mail-order abortion drugs, and the Tennessee Legislature recently sent such protections to Gov. Bill Lee,” said Mallory Carroll, an official with Susan B. Anthony List, an anti-abortion group. “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 would quickly ban all abortion methods if Roe were overturned — including Texas, Missouri, Utah and Tennessee — would be legally prohibited from having telemedicine abortion consultations from any location in their state, even if the doctor were located in a state with legal abortion. Such patients would have to travel to a state where an online, video or phone consultation is legal — the IP address of the computer or phone they were using would identify where they were located. Then, they would have to receive the pills by mail at an address in a state with legal abortion, even if it were a post office box or a hotel.

Some patients are already doing this because they live in one of the states that ban the use of telemedicine for abortion. Some aspects of those laws are unclear, including whether patients who take the pills after returning to their home state are violating their state’s law.

If abortion were completely outlawed in those states, many more patients would travel to states where it was legal, reproductive health experts said.

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 that are currently authorized by the two mifepristone manufacturers to dispense that medication.

But opponents of abortion and states that outlaw abortion are likely to try to challenge or curtail the ability of patients to cross state lines to get the pills, legal experts said. There may be attempts by states that ban abortion to prosecute doctors and other health providers in states where abortion is legal, for example, or to try to block organizations or funds that provide financial help for patients to travel to other states, Ziegler said.

States that support abortion rights are mobilizing to block such efforts. Legislation in California would provide financial assistance to patients traveling from other states to obtain abortions and increase the number of abortion providers. Connecticut just passed a bill that would prevent abortion providers from being extradited to other states, bar Connecticut authorities from cooperating with abortion investigations from a patient’s home state and allow Connecticut residents who are sued under another state’s abortion provision to countersue.