The order follows a temporary decision last week by the same panel of judges to reinstate the ban, less than 48 hours after it was suspended by the lower-court judge. The decision was based on previous rulings in a separate challenge, which said that because the ban is enforced by private individuals, and not government officials, it is not clear when and how the law can be challenged in federal court.

The battle over the law’s enforcement mechanism has effectively halted almost all abortions in Texas, even though no court has addressed whether the ban violates past Supreme Court decisions guaranteeing the right to an abortion until viability, usually about 22 to 24 weeks of pregnancy.

The Supreme Court allowed a Texas law banning abortion past six weeks to remain in effect. Other conservative states may adopt similar measures going forward. (Blair Guild/The Washington Post)

Since Sept. 1, patients seeking to terminate their pregnancies have been driving hours to other states, including Oklahoma and Kansas, according to providers and advocates. Those who lack the money to make such trips, or cannot leave work or child-care commitments, are forced to continue with unwanted pregnancies.

A dozen other states have passed laws that are as restrictive as the one in Texas, which bans abortion after a physician detects cardiac activity in the womb. But federal judges have prevented those laws from taking effect, finding them at odds with Roe v. Wade and other rulings.

But the Texas law was specifically designed to avoid judicial review by making it difficult for abortion providers and individuals seeking access to abortion to challenge it.

The law is enforced by private citizens, rather than state government officials. Individuals can sue anyone who helps a woman get an abortion after the six-week mark. Successful lawsuits result in an award of at least $10,000 to the person who filed the complaint.

The Justice Department sued the state of Texas after the Supreme Court declined to block the law in response to a separate lawsuit filed by abortion providers and advocates.

The high court’s conservative majority said opponents, who had sued state court judges and clerks, raised “serious questions” about the constitutionality of the ban. But the justices allowed the law to remain in effect pending further review, saying the challengers had not shown they were suing the proper defendants.

The 5th Circuit on Thursday said its decision to leave the law in effect was based on the high court’s reasoning and its own previous decision in that case, in which the appeals court said it was not clear that federal courts have a role in reviewing the Texas law.

The order said the appeals court would quickly schedule the Justice Department’s lawsuit to be reviewed by the same panel that will take up the lawsuit from abortion providers in December. On Friday, the court tentatively set argument for the week of Dec. 6.

Texas Attorney General Ken Paxton (R) has argued that the U.S. government cannot sue Texas officials to block the law, because they are not the ones enforcing the ban. Instead, Paxton said in court filings, the only way to directly challenge the constitutionality of the law is to wait until a doctor is sued under its provisions in state court.

Justice Department lawyers and constitutional law scholars counter that the federal government must be permitted to take action to prevent an end-run around the judicial system.

If the abortion ban in Texas is upheld by the courts, they say, state legislatures throughout the country could craft similar laws that infringe on other constitutional rights — the right to own a gun, for example, or to pray in public.

Last week, a federal judge in Austin temporarily suspended enforcement of the abortion ban, saying he would “not sanction one more day of this offensive deprivation of such an important right.”

“A person’s right under the Constitution to choose to obtain an abortion prior to fetal viability is well established,” U.S. District Judge Robert L. Pitman, a nominee of President Barack Obama, wrote in a 113-page ruling. “Fully aware that depriving its citizens of this right by direct state action would be flagrantly unconstitutional, the State contrived an unprecedented and transparent statutory scheme to do just that.”

But the 5th Circuit quickly put Pitman’s order on hold and reinstated the law pending further review.

Elizabeth Wydra, president of the Constitutional Accountability Center, which filed a brief in support of the Justice Department, said Thursday that she expects the federal government to ask the Supreme Court to intervene.

“There is no doubt that the United States has the power to sue to defend itself and its people who have been harmed by Texas’s flagrantly unconstitutional law,” she said in a statement.

Texas Right to Life spokeswoman Kimberlyn Schwartz applauded the court’s order, but said in a statement that “the battle is not finished.”

The outcome on Thursday night from the conservative-leaning appeals court was not unexpected. In a 2018 opinion, Ho lamented the “moral tragedy of abortion.” Both Ho and Haynes were in the majority in an August decision upholding a 2017 Texas statute outlawing a common abortion method used to end second-trimester pregnancies.

In that case, reviewed by a full complement of judges on the 5th Circuit, Stewart joined the dissent, which said the Texas law “under the guise of regulation, makes it a felony to perform the most common and safe abortion procedure employed during the second trimester.”