After a day of whiplash federal court rulings that eventually led to the blocking of Texas’s new boundary-testing immigration enforcement law, the U.S. Fifth Circuit Court of Appeals heard arguments Wednesday on whether Senate Bill 4 should go back into effect while the broader legal case plays out.

SB 4 seeks to make illegally crossing the border a class B state misdemeanor, carrying a punishment of up to six months in jail. Repeat offenders could face a second-degree felony with a punishment of two to twenty years in prison.

It’s designed to give state and local authorities new power to enforce the state’s border with Mexico, a job that has previously been left to the federal government. The law also requires state judges to order migrants returned to Mexico if they are convicted, essentially giving them deportation power. Local law enforcement would be responsible for transporting migrants to the border. A judge could drop the charges if a migrant agrees to return to Mexico voluntarily.

“SB 4 is a modest but important statute,” Texas solicitor general Aaron Nielson told the judges during the hearing. “It’s modest because it mirrors federal law. It’s important because it helps address what even the president has called a border crisis.”

But that argument has faced skepticism inside and outside the courtroom.

The law was initially put on hold by a federal district judge after the federal government and civil rights groups sued to block its implementation. But on Tuesday, the U.S. Supreme Court let it go into effect for about eight hours.

That came after the Fifth Circuit court had issued a stay on the lower court judge’s ruling. But two justices in the high court on Tuesday sent the case back to the appeals court, saying the court had made a procedural error earlier in the proceedings and urging it to issue a ruling promptly.

Hours after Justice Amy Coney Barrett issued her opinion, which was joined by Justice Brett Kavanaugh, the Fifth Circuit hastily scheduled a hearing over Zoom for Wednesday. And late Tuesday night, the appeals court issued a 2–1 ruling that effectively blocked SB 4 again.

The judges on the appeals panel during Wednesday’s morning hearing were: Priscilla Richman, a nominee of George W. Bush; Irma Carrillo Ramirez, a Biden nominee; and Andrew Oldham, a Trump nominee who dissented in Tuesday night’s ruling. Oldham, who was previously the general counsel for Governor Greg Abbott, sounded more sympathetic toward Texas’s lawyer’s arguments, saying that in order for the federal government to win, it needs to prove every provision in the law is unlawful—but because the law hasn’t been enforced, it is just guessing at this point.

“We have no clue how any of this would actually be enforced, because there’s not been a single person who has been arrested, not a single person who has been ordered removed, not a single state judge who’s had occasion to adjudicate a single provision of this in any way. So we’re predicting all of this,” Oldham said.

But Richman, the Bush nominee, appeared skeptical.

At times, the uncertainty surrounding the law was on display in the courtroom Wednesday. Many questions remain unanswered about how and when the law would be enforced.

A judge on the panel asked Nielson how the law would be applied for an immigrant who crossed the border into Arizona or Canada and later moved to Texas.

“I confess, your honor, I don’t know,” Nielson admitted.

Nielson also requested that the appeals court at least let some provisions of the law stand if it prevents other parts from going into effect. He said Texas police should be able to arrest people suspected of crossing the border illegally and turn them over to federal authorities. Richman noted that nowhere in SB 4 does it say police should turn over immigrants to federal immigration agents.

Lawyers for the U.S. Department of Justice and immigrant-rights organizations also presented arguments saying that SB 4 preempts federal law.

They said that SB 4 goes further than Arizona’s SB 1070—a state immigration law that state passed in 2010. The U.S. Supreme Court gutted a provision in that law that allowed police to arrest people they suspected were in the country without legal immigration status. In that case, like in previous federal court rulings, the high court said the federal government has sole jurisdiction over immigration matters.

Another hearing is scheduled for April 2 in the appeals court. It’s unclear when the three-judge panel would issue a ruling.

Tuesday night’s decision caused some observers to suspect that Texas faces long odds on getting the Fifth Circuit to immediately allow the law to go back into effect. Raffi Melkonian, an appellate lawyer in Houston who tuned in to the court hearing, said he doesn’t believe Texas’s lawyer was able to convince the majority of the panel.

“It’s fair to say the panel seemed unconvinced of a stay at the very least,” Melkonian said. He added that Nielson is a smart person but that he may have struggled to answer some of the questions from the panel because “the law doesn’t work correctly.”

“That’s the problem with Texas, because they can’t articulate what they want to do that’s different from enforcing immigration law, which they are not allowed to do,” Melkonian said.

In December, ​​the American Civil Liberties Union and the Texas Civil Rights Project sued Texas on behalf of El Paso County and two immigrant-rights organizations—El Paso–based Las Americas Immigrant Advocacy Center and Austin-based American Gateways—over the new state law.

The following month, the Department of Justice filed its lawsuit against Texas. The lawsuits have since been combined. Last week, Mexican American Legal Defense and Educational Fund and the National Immigration Law Center also filed a lawsuit on behalf of La Unión del Pueblo Entero, an advocacy group in the Rio Grande Valley founded by farmers’ rights activists César Chávez and Dolores Huerta.

This article originally appeared in the Texas Tribune.