WASHINGTON — Even as a federal appeals court said late Wednesday that it would allow the abortion pill mifepristone to remain on the market, it sided with a federal judge in Texas by limiting distribution and access to the drug.

The move potentially makes it much harder for many Americans to get the pill, which is part of a two-drug regimen that now accounts for more than half of the abortions in the United States.

Here’s what is at stake and what could happen next.

The decision by the U.S. Court of Appeals for the Fifth Circuit, in New Orleans, knocked down the most contentious part of the ruling by Judge Matthew J. Kacsmaryk of the Northern District of Texas, who said last week that the Food and Drug Administration had improperly approved the drug.

But the court left in place parts of Judge Kacsmaryk’s decision that could severely curtail nationwide access to mifepristone, further complicating an already thorny case. The decision essentially turns back the clock to 2016, when the F.D.A. added a series of guidelines that eased access to the pill, including by blocking patients from receiving the drug by mail.

Experts say doing so would have significant consequences: Patients would have to take time off work, pay travel costs to get to a medical office and endure the stigma of going in public to seek an abortion, rather than getting the pills discreetly at home.

It also could have implications far beyond abortion, opening the way for single medical providers to sue the F.D.A. to challenge all sorts of medications. Legal experts said the Fifth Circuit’s decision could set up a legal pathway to allow medical providers anywhere in the country to challenge government policy that might affect a patient.

The Justice Department said on Thursday that it would seek emergency relief from the Supreme Court. It did not give a timeline for its application to the court, but it could happen at any moment.

The emergency application would be assigned to Justice Samuel A. Alito Jr., who oversees the Fifth Circuit.

The Supreme Court may, but is not required to, consider the case.

If it takes the case, Justice Alito is likely to first ask for a response from the plaintiffs. The plaintiffs, a group of anti-abortion organizations and doctors, have claimed the pill is unsafe and have argued that the agency’s approval process for the drug was flawed. The timeline and deadline for responses would be set by the court.

The government could then respond to the plaintiffs. The F.D.A., pushing back against the plaintiffs’ claims, countered that the drug was properly approved more than 20 years ago and that it is safe. Although a single justice is empowered to make a decision in an emergency application, by tradition, it will almost certainly go to the full court for consideration.

If the Supreme Court rejects the case, the Fifth Circuit’s decision remains in place.

A second case about the abortion pill is proceeding in a federal courtroom in Washington State.

Less than an hour after Judge Kacsmaryk, a Trump appointee, issued his ruling, Judge Thomas O. Rice of the U.S. District Court for the Eastern District of Washington, an Obama appointee, ordered the F.D.A. to maintain the status quo. He blocked the agency from curbing the availability of mifepristone in the 17 states and District of Columbia that had filed the lawsuit. Judge Rice did not issue a sweeping nationwide injunction, which would affect the entire country. However, the states in that lawsuit represent a majority of states where abortion remains legal.

The Justice Department has asked Judge Rice to clarify what the F.D.A. would be obligated to do if the Texas ruling took effect. Legal experts say that the Fifth Circuit’s decision to block specific parts of the F.D.A.’s rules for the abortion drug puts it in direct conflict with the Washington State case, potentially increasing the chances the Supreme Court will take on the matter.