UPDATE 2-US appeals court weighing fate of Texas border enforcement law

(Adds details from arguments in paragraphs 7-9; Adds comments from Daniel Tenny in paragraphs 18-19)

By Daniel Wiessner

March 20 (Reuters) - A U.S. appeals court on Wednesday began hearing arguments on whether to continue blocking a Republican-backed Texas law that would empower state authorities to arrest and prosecute migrants and asylum seekers for illegally crossing the U.S.-Mexico border.

A three-judge panel of the New Orleans-based 5th U.S. Circuit Court of Appeals is considering whether to allow the law known as SB4 to take effect while the state appeals a judge's ruling that blocked it pending the outcome of a challenge by the administration of Democratic President Joe Biden and civil rights groups.

Aaron Nielson, a lawyer for Texas, told the panel in opening remarks that SB4 mirrors U.S. immigration law and the judge was wrong to rule that it would interfere with federal enforcement.

“Texas has a right to defend itself,” Nielson said.

But he seemed to struggle to answer questions about how the law would work in practice from Circuit Judge Priscilla Richman, who noted that no other state has claimed the right to remove people in the country illegally.

"This is not a power that has been exercised historically by states," she said.

Circuit Judge Andrew Oldham told Daniel Tenny, a U.S. Department of Justice lawyer who represents the Biden administration, that he was skeptical the Biden administration could show that the entire law was likely invalid, which is required to continue to temporary block it.

“When it comes to who gets to be in the United States, that’s exclusively federal. But that’s not what we’re talking about,” said Oldham, an appointee of former President Donald Trump.

Oldham was previously general counsel to Republican Texas Governor Greg Abbott, who has repeatedly clashed with the Biden administration over border security.

Tenny in response said that the entire law interferes with federal enforcement, but that the 5th Circuit could narrow the block on the law to specific provisions that it finds problematic.

The 5th Circuit had initially paused the ruling blocking SB4 and the U.S. Supreme Court upheld that decision on Tuesday, briefly allowing Texas to enforce the law. But in an unusual move hours later, the 5th Circuit panel reversed its earlier ruling in a 2-1 vote.

The dispute over the Texas law is one in a series of legal battles between Republican state officials and the Biden administration over the state's ability to police the border. Texas officials have blamed Biden for an influx in illegal border crossings that they have said drains states resources and threatens public safety, but the administration has said interference from Texas and other states only compounds the problem.

LEGAL BATTLE

SB4 would make it a state crime to illegally enter or re-enter Texas from a foreign country and would give state and local law enforcement the power to arrest and prosecute violators. It also would allow state judges to order that individuals leave the country, with prison sentences up to 20 years for those who refuse to comply.

The statute was signed by Abbott in December. The Biden administration sued in January to stop the law, arguing that it violates the U.S. Constitution and federal law by interfering with the U.S. government's power to regulate immigration as well as running afoul of a 2012 Supreme Court precedent.

Texas has challenged a number of federal immigration policies in court, including the U.S. government's destruction of razor-wire fencing the state has placed along the border, while the Biden administration is suing to force the state to remove a 1,000-foot-long floating barrier in the Rio Grande river.

In a statement on Tuesday responding to the Supreme Court decision, White House Press Secretary Karine Jean-Pierre said the Texas law will "burden law enforcement and sow chaos and confusion at our southern border."

Texas Attorney General Ken Paxton praised the Supreme Court ruling in a statement on Tuesday, before the 5th Circuit decision blocking enforcement of the law. Paxton said he intended "to defend Texas and its sovereignty."

U.S. District Judge David Ezra in blocking SB4 last month agreed with the Biden administration that the state law was invalid under a 2012 U.S. Supreme Court ruling involving an Arizona immigration law that said states cannot adopt immigration enforcement schemes that clash with federal law.

Tenny on Wednesday told the 5th Circuit that upholding SB4 would mean every state could adopt its own policies that potentially clash with federal law.

“This entire scheme is exactly what the Supreme Court warned against in Arizona,” Tenney said. “The federal government has to have control over the immigration system.”

Along with Richman and Oldham, the 5th Circuit panel includes Circuit Judge Irma Carrillo Ramirez, a Biden appointee.

(Reporting by Daniel Wiessner in Albany, New York, Editing by Will Dunham, Alexia Garamfalvi and Aurora Ellis)