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The Supreme Court on Monday heard oral arguments concerning a Texas law that has banned most abortions in the state.

The Texas law known as S.B. 8 would ban most abortions at about six weeks, when a fetal heartbeat may be detected. The justices are hearing arguments in two cases over whether abortion providers or the Justice Department can mount federal court challenges to the law.

ABORTION BACKERS AT SUPREME COURT ARE AIMING FOR ROE V. WADE 'PART 2' IN TEXAS, STEPHEN MILLER WARNS

Pro-choice demonstrators rally outside the U.S. Supreme Court on Nov. 1, 2021, in Washington, D.C. On Monday, the Supreme Court is hearing arguments in a challenge to the controversial Texas abortion law which bans abortions after six weeks. (Photo by Drew Angerer/Getty Images)

Pro-choice demonstrators rally outside the U.S. Supreme Court on Nov. 1, 2021, in Washington, D.C. On Monday, the Supreme Court is hearing arguments in a challenge to the controversial Texas abortion law which bans abortions after six weeks. (Photo by Drew Angerer/Getty Images)

The issue being argued is who can be sued — including state judges and court clerks, who would oversee any litigation. In the initial lawsuits, the abortion clinics had sued those judicial officials, since state executive officers would not have that authority to enforce S.B. 8. 

That "gateway" issue will be key for the state and federal courts poised to continue hearing the case in coming months. The state has argued judicial officers are not responsible for enforcing the abortion restriction and can’t be sued.

In neither case is the right to an abortion directly at issue, but the motivation for lawsuits filed by abortion providers and the Justice Department is that the Texas law conflicts with landmark Supreme Court rulings that prevent a state from banning abortion early in pregnancy.

In the first case, attorney Marc Hearron, representing a coalition of abortion providers, called the Texas law a "roadmap" for any state to oppose federal lawsuits with which it disagreed — since it puts enforcement of law in private hands, not state officials themselves. He argued that providers have the legal right to sue Texas officials, state judges and clerks.

Texas Solicitor General Judd Stone, arguing in defense of the law, said it was not "appropriate" to sue judicial officers. 

"The attorney general simply doesn't have any control of the procession of S.B. 8 lawsuits in any way," he said. 

Pro-choice demonstrators outside of the U.S. Supreme Court in Washington, D.C., on Nov. 1, 2021. (Photo by MANDEL NGAN/AFP via Getty Images)

Pro-choice demonstrators outside of the U.S. Supreme Court in Washington, D.C., on Nov. 1, 2021. (Photo by MANDEL NGAN/AFP via Getty Images)

In the second case, concerning the Biden administration's lawsuit against the Texas law, U.S. Solicitor General Elizabeth Prelogar, who was confirmed by the Senate last week, argued the law is "an attack on the authority of this court to say what the law is."

Prelogar said federal jurisdiction is appropriate and the state of Texas itself — not private citizens — are ultimately liable for its unconstitutionality.

A key precedent here is Ex parte Youngwhere the Supreme Court in 1908 permitted lawsuits in federal courts for injunctions to block allegedly unconstitutional state action — specifically allowing suits against state officials, in lieu of states themselves, for violations of federal law. Stone argued Ex parte Young does not provide a way for federal court intervention, at least until state courts first get a say.

But Prelogar called the law an attack on federal law and the Supreme Court, and said states cannot "flout" immediate federal judicial review.  

"Texas designed S.B. 8 to thwart the supremacy of federal law in open defiance of our constitutional structure," she said. "States are free to ask this court to reconsider its constitutional precedents, but they are not free to place themselves above this court, nullify the Court’s decisions in their borders, and block the judicial review necessary to vindicate federal rights."

Justice Elena Kagan sarcastically called the state legislators who wrote the law "some geniuses" who intended to chill abortion and bypass the legal concept that "states are not to nullify federal constitutional rights'' such as Roe v. Wade.

Maria Peña holds a rosary and sign outside a building housing an abortion provider in Dallas, Thursday, Oct. 7, 2021. (AP Photo/LM Otero)

Maria Peña holds a rosary and sign outside a building housing an abortion provider in Dallas, Thursday, Oct. 7, 2021. (AP Photo/LM Otero) (AP Photo/LM Otero)

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Protesters on both sides of the abortion issue gathered outside the Supreme Court during the oral arguments.

On Dec. 1, the justices will hear a separate challenge to the decisions in Roe v. Wade and Planned Parenthood v. Casey in a case over Mississippi’s ban on abortion after 15 weeks. 

The Associated Press contributed to this report.