Sign up for The Brief, The Texas Tribune’s daily newsletter that keeps readers up to speed on the most essential Texas news.

The U.S. Supreme Court on March 12 said it will continue to temporarily block a new state law that allows Texas police to arrest people suspected of illegally crossing the Texas-Mexico border.

Justice Samuel Alito extended his stay until March 18.

The nation's highest court is overruling a decision from the 5th U.S. Circuit Court of Appeals that would have allowed police to start enforcing Senate Bill 4 on March 9.

That 5th Circuit ruling came just a day after U.S. District Judge David Ezra in Austin blocked SB 4 from going into effect, saying the law “threatens the fundamental notion that the United States must regulate immigration with one voice.”

Gov. Greg Abbott signed SB 4 in December, marking Texas’ latest attempt to try to deter people from crossing the Rio Grande after several years of historic numbers of migrants arriving at the Texas-Mexico border.

SB 4 seeks to make illegally crossing the border a Class B 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 20 years in prison.

The law also requires state judges to order migrants returned to Mexico if they are convicted; 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.

In December, ??the American Civil Liberties Union, the ACLU of Texas 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 U.S. Department of Justice filed its lawsuit against Texas. The lawsuits have since been combined.

On March 12, Mexican American Legal Defense and Educational Fund and the National Immigration Law Center also filed a lawsuit on behalf of La Union del Pueblo Entero, an advocacy group in the Rio Grande Valley founded by farmer rights activists César Chávez and Dolores Huerta. In its lawsuit, the immigrant rights groups say that "every arrest under the illegitimate power of S.B. 4 is an unconstitutional seizure, and that Texas’ imposition of a criminal penalty of banishment constitutes cruel and unusual punishment under the Constitution."

The Supreme Court proceedings come during a presidential election year when immigration has been top of mind for many voters. Former President Donald Trump has bashed President Joe Biden for his immigration policies, saying he has incentivized illegal immigration. Biden has created some narrow paths for migrants to enter the U.S. legally with policies that seek to deter migrants from entering the country illegally.

We can’t wait to welcome you to downtown Austin Sept. 5-7 for the 2024 Texas Tribune Festival! Join us at Texas’ breakout politics and policy event as we dig into the 2024 elections, state and national politics, the state of democracy, and so much more. When tickets go on sale this spring, Tribune members will save big. Donate to join or renew today.

This article originally appeared in The Texas Tribune at https://www.texastribune.org/2024/03/04/texas-sb4-illegal-immigration-law-5th-circuit-court-ruling/.

The Texas Tribune is a member-supported, nonpartisan newsroom informing and engaging Texans on state politics and policy. Learn more at texastribune.org.