(Reuters) - A federal appeals court has upheld an order blocking Arkansas state restrictions on abortions after 18 weeks and abortions performed because of a fetal test indicating Down syndrome.

The unanimous panel of the 8th U.S. Circuit Court of Appeals on Tuesday ruled that both restrictions, which had been challenged by the Little Rock Family Planning Services, a clinic that performs abortions, ran afoul of clear Supreme Court precedent holding that abortion cannot be restricted before a fetus is viable. That threshold is generally agreed to be at 24 weeks.

However, two of the judges on the panel wrote in a concurrence that the Supreme Court should reconsider the issue.

"Following the 8th Circuit's decision against Arkansas's late-term abortion ban and Down-syndrome-selection ban, I plan to seek further review of this decision in order to uphold Arkansas's laws which protect the lives of the unborn and the health of the mothers," Arkansas Attorney General Leslie Rutledge said in a statement.

"We're pleased with the 8th Circuit's ruling," said Kendall Turner of O'Melveny & Myers, a lawyer for the clinic. "As a result of this decision, people in Arkansas will continue to be able to exercise their constitutionally protected right to access abortion care."

Little Rock Family Planning sued the state in 2019 in the Eastern District of Arkansas, challenging two recently enacted state laws – Act 493, the 18-week abortion ban, and Act 619, the ban on abortion because of Down syndrome. It argued both were unconstitutional, citing Planned Parenthood v. Casey, which established the viability threshold for abortion restrictions.

U.S. District Judge Kristine Baker agreed, enjoining the laws, and the state appealed.

It argued that the bar against pre-viability restrictions was not absolute. It noted that Casey had upheld a parental consent requirement, though that could be bypassed by a judge, and that the Supreme Court in 2007 had upheld a ban on certain abortion procedures in Gonzales v. Carhart.

Circuit Judge James Loken, writing for the panel on Tuesday, rejected those arguments, saying both those earlier precedents had preserved the right to pre-viability abortion.

"The Supreme Court has repeatedly stated that its pre-viability rule is categorical," he wrote. Both of the challenged laws, he said, "effectively prohibits a substantial universe of pre-viability abortions."

Circuit Judge Bobby Shepherd wrote a separate concurrence, joined by Circuit Judge Ralph Erickson, urging the Supreme Court to reconsider the categorical bar. He said the issue of "eugenic" abortion of Down syndrome fetuses warranted additional attention.

"Act 619, which prohibits a physician from performing or attempting to perform an abortion based on a diagnosis or suspicion of Down Syndrome involves significant and, as yet, unconsidered issues regarding the balance of interests when the sole reason a woman seeks an abortion is what she deems an unwanted immutable characteristic of the unborn child," he said.

The Supreme Court's conservative majority has expanded during President Donald Trump's term, with the appointments of Justices Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett, raising the possibility that the court could change course next time it hears an abortion-related case.

The case is Little Rock Family Planning Services v. Rutledge, 8th U.S. Circuit Court of Appeals, No. 19-2690.

For Arkansas: Vincent Wagner of the Arkansas Attorney General's Office

For Little Rock Family Planning: Kendall Turner of O'Melveny & Myers