RICHMOND, Va. (AP) — A federal appeals court appeared skeptical Tuesday as civil rights groups sought to allow legal challenges to President Donald Trump’s ban on travelers from predominantly Muslim countries to move forward despite a 2018 U.S. Supreme Court ruling upholding the ban.

The ban, put in place just a week after Trump took office in January 2017, sparked an international outcry from Muslim advocates and others who said it was rooted in religious bias. Now in its third iteration, the ban applies to travelers from Iran, Libya, Somalia, Syria and Yemen. It also affects two non-Muslim countries, keeping out travelers from North Korea and some Venezuelan government officials and their families.

A three-judge panel of the 4th U.S. Circuit Court of Appeals in Richmond is being asked to decide whether a federal judge in Maryland made a mistake when he refused to dismiss three lawsuits after the Supreme Court found in a separate case that the travel ban has a “legitimate grounding in national security concerns.”

Mark Mosier, an attorney representing U.S. citizens and permanent residents whose relatives have been unable to enter the U.S. because of the ban, asked the court to allow the legal challenges to proceed in court.

Mosier argued that the Supreme Court rejected a preliminary injunction to block the travel ban, but did not decide the merits of the constitutional claims made in the lawsuits. The plaintiffs argue that the travel ban violates the First Amendment’s Establishment Clause, which prohibits the government from favoring one religion over another.

Mosier said the lawsuits should be allowed to proceed so the plaintiffs can gather evidence on their claim that the travel ban is rooted in anti-Muslim bias and that the Trump administration’s claim of national security concerns is a pretext for the policy.

But the judges — all nominated by Republican presidents — repeatedly questioned Mosier about the Supreme Court’s finding in a Hawaii case that there is a plausible rationale to support the travel ban.

Judge Julius Richardson cited the Supreme Court’s rejection of claims that Trump’s own tweets and statements should be considered to show that the policy is rooted only in anti-Muslim bias. During the presidential campaign, Trump called for “a complete and total shutdown of Muslims entering the United States.”

Trump has said the ban is aimed at making the U.S. safer from potentially hostile foreigners.

“It’s hard to see how we ignore Hawaii,” Richardson said, referring to the Supreme Court ruling.

Joshua Waldman, an appellate attorney with the U.S. Department of Justice, said the Supreme Court “rejected precisely the same arguments” being made by the challengers in the Maryland cases.

Waldman asked the court to reverse a ruling from U.S. District Court Judge Theodore Chuang, who said the lawsuits should move forward to the discovery phase, when the plaintiffs have said they would seek records from the Trump administration on the origins of the ban and how it has been enforced over the last three years.

Federal appeals courts — including the 4th Circuit — had upheld rulings from federal judges who blocked the travel ban from taking effect. But the Supreme Court came to a different conclusion.

In a 5-4 ruling, Chief Justice John Roberts wrote that the travel ban was well within U.S. presidents’ considerable authority over immigration and responsibility for keeping the nation safe.

After the hearing before the 4th Circuit on Tuesday, about 40 civil rights advocates held a rally outside the courthouse and said they will continue to fight the travel ban.

Mana Kharrazi, an Iranian-American who is a plaintiff in one of the Maryland challenges, said the travel ban affects families in many ways, preventing them from attending weddings, births, funerals and other milestone events.

“Ultimately, this is dividing our families and keeping us apart,” Kharrazi said. “I’m standing her for thousands of people that are unable to be here.”