(THE HILL) – The Supreme Court on Monday heard arguments over whether legal challenges to Texas’s controversial six-week abortion ban can be heard in federal court. 

The case did not deal directly with the ban’s lawfulness. Rather, the justices wrestled with whether the Department of Justice (DOJ) and abortion providers can bring federal lawsuits against Texas or state officials in an effort to block the law.

The challengers argued that Texas has effectively nullified the constitutional right to abortion and urged the justices to rule that federal courts may review, and potentially halt or invalidate, the six-week ban.

“The rules that have been created by the Texas legislature … turn the courts into a weapon that can be used to nullify constitutional right,” said Marc Hearron, who represented the abortion providers. 

Monday’s case marked the second time S.B. 8 has reached the justices. In a previous 5-4 ruling, which broke largely along familiar ideological lines, the conservative-majority court denied abortion providers’ emergency request to block the law.

Since that Sept. 1 ruling — which did not address the measure’s constitutionality — litigation over the law, known as S.B. 8, has percolated back up to the Supreme Court, while abortions in Texas have been curtailed.

The question of whether federal court is a proper forum to hear S.B. 8 challenges is complicated by the law’s unique legislative design, which critics have likened to a “bounty” system.

S.B. 8 authorizes citizens to file private lawsuits against those who perform, aid or abet an abortion after fetal cardiac activity is detected, typically around six weeks of pregnancy — before most women know they are pregnant. Successful suits under S.B. 8, which contains no exceptions for rape or incest, fetch at least $10,000.

Judd Stone, the solicitor general of Texas, said the challengers should not be permitted to bring federal suits against Texas or state officials because, by design, state actors are not charged with enforcing S.B. 8.

Texas’s six-week ban is among hundreds of abortion restrictions that state legislatures have passed in recent years. Many such measures have the explicit goal of overturning Roe v. Wade, the landmark 1973 ruling that recognized a constitutional right to abortion before a fetus is viable, typically around 24 weeks of pregnancy.

The justices next month will hear arguments over a 15-week abortion ban in Mississippi. But while the Mississippi ban presents a straightforward clash with settled Supreme Court precedent, Texas’s atypical enforcement mechanism has thrown a wrench in the normal operations of judicial review.

The dispute over S.B. 8 arose after a group of abortion providers, led by Whole Woman’s Health, brought a federal lawsuit this summer to block the law prior to its Sept. 1 effective date. The group identified Texas state court clerks and judges as defendants, as well as a private person whom the abortion providers believed would try to enforce S.B. 8.

The Texas defendants asked the federal judge overseeing the dispute to dismiss the case, which he declined to do, prompting them to appeal. The U.S. Court of Appeals for the 5th Circuit, siding with the defendants, agreed to pause the district court proceedings and declined to temporarily block the six-week abortion ban in the interim.

Whole Woman’s Health then filed an emergency petition to the Supreme Court asking the justices to halt the Texas restriction. The court on Sept. 1 voted 5-4 to deny the emergency request, with Chief Justice John Roberts joining the court’s three more liberal justices in dissent.

The majority, citing the “complex and novel” procedural questions raised by S.B. 8’s outsourcing of enforcement power to private citizens, said it was unclear whether the named defendants in suit “can or will seek to enforce the Texas law against the applicants in a manner that might permit our intervention.”

A week later the DOJ sued the state of Texas in federal court, seeking to block the law. The U.S. district judge agreed to temporarily halt the law, but the 5th Circuit reinstated S.B. 8 while the case proceeded through the courts. 

The DOJ asked the Supreme Court to address the matter. The justices agreed to do so, combining the Whole Woman’s Health and DOJ cases for the purpose of addressing whether federal courts can hear their disputes and potentially block or strike down Texas’s six-week abortion ban.