By Andrew Chung and Lawrence Hurley

WASHINGTON (Reuters) – Conservative U.S. Supreme Court justices on Monday appeared to lean toward allowing a challenge by abortion providers to a Texas law that imposes a near-total ban on the procedure and lets private citizens enforce it, but seemed skeptical about whether President Joe Biden’s administration can do so.

The court, with a 6-3 conservative majority, heard three hours of oral arguments in separate challenges by abortion providers and the Democratic president’s administration to the Republican-backed measure considered the toughest abortion law in the United States.

Some justices signaled that existing Supreme Court precedent could accommodate the lawsuit brought by abortion providers despite the law’s novel design that makes it difficult for federal courts to block its enforcement. Instead of having state officials enforce a ban on abortions after about six weeks of pregnancy – a time when many women do not realize they are pregnant – the law lets individual citizens enforce it through lawsuits against providers.

U.S. abortion rights are hanging in the balance as the justices review the Texas law before hearing arguments on Dec. 1 over the legality of a Mississippi measure prohibiting the procedure after 15 weeks of pregnancy.

As the Texas challenges are being heard on an expedited basis, a decision potentially blocking the law could come quickly. In the challenge by abortion providers, the court on Sept. 1 declined to halt the law, with five of its six conservative justices in the majority. There were signs on Monday that some conservative justices were reconsidering their positions.

However, in the Biden administration’s challenge, conservative justices seemed skeptical about federal power to sue Texas over the law.

At issue is whether federal courts can hear lawsuits aimed at striking down the Texas law and whether the U.S. government even can sue to try to block it. If the justices keep federal courts out of the process by virtue of the law’s unique design, it could be replicated in other states and curtail abortion access in other parts of the country.

Justice Amy Coney Barrett asked clinic lawyer Marc Hearron about whether under the law’s structure the constitutional claims on the right to abortion could ever be “fully aired.” Under the Texas law, abortion providers can bring up that constitutional issue as a defense only after they have been sued.

Justice Brett Kavanaugh expressed interest in an outcome raised by liberal Justice Elena Kagan in which state court clerks would be barred from allowing lawsuits brought by private individuals seeking to enforce the law to proceed while litigation over the legality of the measure unfolds.

Kavanaugh wondered whether the court should close a loophole that he said the Texas law “exploited” in its precedents concerning when state officials can be barred from enforcing unconstitutional laws.

Kavanaugh also pondered if states could pass similar laws that could infringe other constitutional rights including gun rights. A state, for example, could allow for $1 million in damages against anyone who sells an AR-15 rifle, he said.

His tone was more skeptical during the argument over the Biden administration’s September lawsuit aimed at stopping the Texas measure, describing it as “different and irregular and unusual.”

Kagan said the law was written by “some geniuses” to evade the broad legal principle that “states are not to nullify federal constitutional rights.”

Like Kavanaugh, Kagan warned of the consequences of states passing laws that infringe upon rights, including same-sex marriage and religious liberty. If the Texas law remains, “we would live in a very different world to the world we live in today,” she said.

Conservative justices Clarence Thomas and Samuel Alito raised the question of whether anyone would have standing to sue under the Texas law without having a direct injury. Texas Solicitor General Judd Stone, defending the law, said “outrage” based on abortion opposition would be grounds to bring a lawsuit.

In the Biden administration’s challenge, conservative Chief Justice John Roberts questioned Solicitor General Elizabeth Prelogar on the “limiting principle” for the federal government suing states, noting that a different administration could also try to directly challenge states over their laws. Other conservative justices expressed similar doubts.

The Texas and Mississippi laws are among a series of Republican-backed abortion restrictions pursued at the state level in recent years. Lower courts blocked the Mississippi law.

LANDMARK RULING

Abortion opponents hope the Supreme Court will roll back abortion rights or even overturn its 1973 Roe v. Wade decision that recognized a woman’s constitutional right to terminate a pregnancy and legalized the procedure nationwide.

The Texas measure enables private citizens to sue anyone who performs or assists a woman in getting an abortion after cardiac activity is detected in the embryo. That feature made it more difficult to directly sue the state. Individual citizens can be awarded a minimum of $10,000 for bringing successful lawsuits under the law. Biden’s administration has called it a “bounty.”

The Texas law has an exception for a documented medical emergency but not for pregnancies resulting from incest or rape.

The law’s design has deterred most abortions in Texas, which is the second most populous U.S. state, behind only California, with about 29 million people.

The Texas dispute reached the Supreme Court with unusual speed. The justices agreed to take up the matter on Oct. 22, bypassing lower courts that are considering the challenges.

(Reporting by Andrew Chung and Lawrence Hurley in Washington; Additional reporting by Jan Wolfe; Editing by Will Dunham)