Texas SB 4: What to know about the state's controversial immigration law opposed by the Biden administration

A federal appeals court heard arguments over SB 4 on Wednesday.

Migrants line up for processing in Eagle Pass, Texas.
Migrants who crossed the Rio Grande and entered the United States from Mexico are lined up for processing by U.S. Customs and Border Protection in Eagle Pass, Texas, in September 2023. (Eric Gay/AP)

A federal appeals court heard arguments Wednesday over a controversial Texas law that allows state law enforcement to arrest and detain people they suspect of entering the country illegally.

🔎 What does the law do?

The law, known as Texas Senate Bill (or SB) 4, was passed in 2023 and signed into law by Texas Gov. Greg Abbott. It allows police in the Lone Star State to arrest people suspected of illegally crossing the Mexico border into the state. It was supposed to go into effect earlier this month, but the Justice Department challenged it, leading to numerous court delays.

↘️ What happened in court?

The U.S. Supreme Court on Tuesday cleared the way for the law to take effect, pending further action from an appeals court that has been weighing its merits. Hours later, that court, the 5th U.S. Circuit Court of Appeals in New Orleans, blocked the law while deciding whether to allow Texas officials to temporarily enforce it. The appellate court’s three-judge panel heard arguments from both sides Wednesday.

📢 What did Texas say?

National Guard soldiers patrol a dirt road in 2024 in Eagle Pass.
National Guard soldiers patrol a dirt road in Eagle Pass, Texas, on Wednesday. (Brandon Bell/Getty Images)

Texas Solicitor General Aaron Nielson argued that the state, which has become a flashpoint for the migrant crisis, has the right to protect its own borders because the federal government is not doing a sufficient job enforcing U.S. immigration laws

📢 What did the DOJ say?

Daniel Tenny, an attorney for the Justice Department, argued that U.S. border enforcement is “fundamentally an international exercise” and that the federal government is ultimately responsible for enforcing U.S. immigration laws.

▶️ An unprecedented case

The Supreme Court building.
The Supreme Court building. (J. Scott Applewhite/AP)

During arguments Wednesday, Fifth Circuit Chief Judge Priscilla Richman, who was appointed by former President George W. Bush, noted the unprecedented nature of the case.

“This is the first time, it seems to me, that a state has claimed that they have the right to remove illegal aliens,” Richman said. “I mean, this is not a power that historically has been exercised by states.”

What did the Supreme Court say?

The case is likely to wind up back at the Supreme Court. In penning the opinion for the 6-3 conservative majority, Justice Amy Coney Barrett wrote that “the time may come” for the nation’s high court to review the law, but that it was too “premature” to do so Tuesday.

She added that if the 5th Circuit doesn’t issue a decision soon, the Biden administration could return the case to the Supreme Court.

🇺🇸 How did the White House respond?

President Biden delivers his State of the Union address.
President Biden delivers his State of the Union address on March 7. (Matt McClain/The Washington Post via Getty Images)

The White House blasted the Supreme Court’s ruling.

“We fundamentally disagree with the Supreme Court’s order allowing Texas’ harmful and unconstitutional law to go into effect,” White House press secretary Karine Jean-Pierre said in a statement. “S.B. 4 will not only make communities in Texas less safe, it will also burden law enforcement, and sow chaos and confusion at our southern border.”

The law, she said, is “just another example of Republican officials politicizing the border while blocking real solutions.”

🇲🇽 How Mexico has responded

Mexico opposes SB 4. In a statement on Tuesday, the country's foreign affairs ministry said Mexico will not accept migrants who have been deported from the U.S. under the Texas law.

In a friend-of-the-court brief filed on Thursday, Mexico said there would be "substantial tension" between Mexico and the U.S. if the law takes effect.