The Justice Department asked the Supreme Court on Monday for an emergency halt to what it called a “plainly unconstitutional” Texas law that has practically stopped access to abortion in the second-largest state.

The action means the court will again have to confront the controversial law, Texas S.B. 8, which generally outlaws the procedure after six weeks of pregnancy. In a divisive 5-to-4 decision last month, the court allowed the law to go into effect, although dissenters said it violated the precedent in Roe v. Wade that guaranteed a right to abortion before fetal viability.

The Biden administration raises different arguments in its new filing, and says the court must intervene to prevent an end run around its authority and the Constitution. “Texas designed S.B. 8 to violate the Constitution, as interpreted by this Court, and to thwart judicial review,” Acting Solicitor General Brian H. Fletcher wrote in his filing. He added, “That proposition is as breathtaking as it is dangerous.”

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)

Allowing the law to remain in place, Fletcher said, would perpetuate “the ongoing irreparable injury to the thousands of Texas women who are being denied their constitutional rights,” he added.

The court told Texas to respond to the filing by Thursday, indicating it could act within days. And it also called for a response on that day to a request by abortion providers to speed consideration.

Both the providers and the administration are asking for the law to be suspended, and for the Supreme Court take up the issue this term, before the U.S. Court of Appeals for the Fifth Circuit considers the merits of the law. The Supreme Court does that only rarely, but the action on Monday indicates the justices at least are considering it.

An upcoming Supreme Court review of a Mississippi abortion law could pave the way for many other state laws that restrict or ban the procedure. (Joshua Carroll/The Washington Post)

The developments add more drama to a Supreme Court term that will determine how far the six-justice conservative majority could go in redefining the court’s abortion jurisprudence.

That the court was willing initially to allow the Texas law to go into effect was a sign that its newest members, all chosen by President Donald Trump, are open to reconsidering precedents. Three of the dissenters said the law was flatly unconstitutional. On Dec. 1, the high court will hear a challenge to a Mississippi law that conservatives have urged the court to use to overturn the constitutional right to abortion established by Roe v. Wade and reaffirmed in Planned Parenthood v. Casey in 1992.

Mississippi’s law would ban most abortions after 15 weeks, and was struck down by lower courts as a clear violation of Supreme Court precedent on viability. That limit is generally gauged to be 22 to 24 weeks.

The Supreme Court previously has turned away petitions from states where laws prohibiting abortions before that time span were blocked by lower courts. So the decision to take Mississippi’s challenge was significant. More than 125 amicus briefs have been filed in the case.

Texas’s law is far more restrictive. It bars most abortions after cardiac activity is noted in the embryo. That can be as early as six weeks into a pregnancy, when many people do not realize they are pregnant. Moreover, the law makes no exceptions for rape or incest.

It, too, would probably have been struck down, except for an enforcement mechanism specifically designed to avoid federal court review.

Usually in challenging abortion restrictions, opponents seek to enjoin government officials from enforcing laws that violate constitutional protections. But the Texas law is enforced by private citizens rather than the state government. Any individual can sue anyone who helps a woman get a prohibited abortion. Successful lawsuits would result in an award of at least $10,000 to the person who filed the complaint.

When the Supreme Court considered a request to keep the law from going into effect, the majority’s one-paragraph opinion cited the law’s “complex and novel” procedural questions, and said it was not clear that abortion providers challenging the law were suing the proper defendants.

It also acknowledged concerns about the constitutionality of the measure. Chief Justice John G. Roberts Jr., who dissented, said that because the enforcement regime was “not only unusual, but unprecedented,” it deserved more judicial scrutiny before being allowed.

The court’s three liberal justices aligned in a dissent that said the law was “flagrantly unconstitutional.” The Justice Department entered the fight after that, in a suit that said Texas officials could be sued.

A federal district judge agreed and said he would “not sanction one more day of this offensive deprivation of such an important right.” But a panel of the U.S. Court of Appeals for the Fifth Circuit that covers the state of Texas would not allow the injunction to remain in place. It has set both cases challenging the law for a hearing in December.

Monday’s Justice Department filing said the Texas law “has made abortion effectively unavailable in Texas after roughly six weeks of pregnancy. Texas has, in short, successfully nullified this Court’s decisions within its border.”

It notes that one of the architects of the law, former Texas solicitor general Jonathan Mitchell, said in a brief in the case that its design “has boxed out the judiciary” and asserts that states “have every prerogative to adopt interpretations of the Constitution that differ from the Supreme Court.”

However, if that were the case, the administration argues in its filing, the states would actually be able to “nullify disfavored constitutional rights by purporting to disclaim their own enforcement authority and delegating enforcement of unconstitutional laws to private bounty hunters.”

A state might deputize the public to search out gun ownership, or those who make protected campaign donations, the filing said. The lower court, the administration said, “correctly determined that the State’s ingenuity does not permit it to nullify constitutional rights in that manner.”

Ann Marimow contributed to this report.