Originally Published: 21 DEC 23 06:15 ET

Updated: 21 DEC 23 10:11 ET

By Nicole Chavez, Rosa Flores and Sara Weisfeldt, CNN

(CNN) — A new law that makes entering Texas illegally a state crime is sowing confusion and uncertainty among undocumented migrants and mixed status families along the US-Mexico border, according to immigration advocates.

Many of those advocates tell CNN they fear a wave of racial profiling as well as detentions and attempted deportations by state authorities when the law is expected to take effect in March.

“There are a lot of unknowns about how this law will be implemented,” Houston immigration attorney Roberto Quijano said a recent town hall meeting about the law.

Republican Gov. Greg Abbott signed the measure, Senate Bill 4, into law on Monday, granting local law enforcement the power to arrest migrants and judges the ability to issue orders to remove them to Mexico, in a state where Latinos represent 40% of the population.

“We have a lot of concerns about racial profiling and racism,” Ramona Casas, a community organizer with the nonprofit Arise Adelante, said this week at a protest against SB4. “These laws open the door for that. They threaten families.”

Casas said she believes Latinos in Texas will be forced to carry their passports and IDs at all times in order to avoid being detained on suspicion of being undocumented.

For many opponents the new law harkens to a similar 2010 “Show me your papers” law in Arizona – which was largely struck down by the US Supreme Court two years later. The high court concluded in 2012 that the federal government had the power to block the law but let stand a controversial provision allowing police to check a person’s immigration status while enforcing other laws if “reasonable suspicion” existed that the person is in the United States illegally.

Critics have said the new Texas law is unconstitutional and civil rights groups filed a lawsuit against the state on Tuesday.

The American Civil Liberties Union, the ACLU of Texas, and the Texas Civil Rights Project argued that the controversial border law is unconstitutional because it preempts federal law.

“Immigration is a quintessentially federal authority,” the organizations argue, according to the lawsuit.

The enforcement of immigration law typically falls under the purview of the federal government, not individual state governments. Asked this week whether President Joe Biden supported the federal government taking legal action on the matter, White House press secretary Karine Jean-Pierre said the Department of Justice would decide whether a lawsuit would be filed and that she was “not going to get ahead of that.”

CNN has reached out to Abbott’s office and the defendants for comment on the lawsuit.

Late last month, the executives of El Paso county – as well as Harris county, which is home to Houston, and Travis county, where Austin is located – penned a letter to Biden, urging him to stop SB 4 from going into effect, citing concerns about the measure’s constitutionality and whether it will truly make communities safer. The three counties represent nearly a quarter of the state’s population.

The new law comes amid a surge of migrants on the southern border that has placed pressure on local, state and federal authorities to crack down on illegal crossings.

On Tuesday alone, US Border Patrol processed 10,500 migrants who crossed the US-Mexico border unlawfully, according to a Homeland Security official. Current and former US officials have warned that the current pace of arrests is pushing federal resources to the limit, with the system nearing a “breaking point.” There are over 26,000 migrants in border custody, the official said.

Frustrated by what Abbott says is the federal government’s failure to secure the border, the governor is giving state law enforcement new powers to detain and deport migrants.

Abbott and the Biden administration have sparred over some of the state’s measures to curb illegal immigration along the southern border.

Harris County Judge Lina Hidalgo told reporters Tuesday that the state was using SB4 to “weaponize immigration … to score political points.”

“Just in Harris County, there are 500,000 undocumented immigrants. These individuals work hard like all of us and they face crime like any of us. They’re survivors of domestic violence. They want to protect their children and their families. Now they’re going to feel like they can’t call the police because the police is … ICE,” said Hidalgo, referring to US Immigration and Customs Enforcement.

Immigration advocates caution the new law will give local law enforcement officers the power of federal immigration agents and lead to more harassment and abuse in border communities.

Marisa Limón Garza, executive director at Las Americas Immigrant Advocacy Center in El Paso, Texas, warned that SB4 would expose countless US citizens, mixed status households, and undocumented immigrants to unlawful interrogations, searches, seizures, and arrests “based on how ‘foreign’ they look and how they behave.”

Dylan Corbett, executive director of the Hope Border Institute in El Paso, said the new law would criminalize people seeking safety at the border and instill fear in families throughout Texas.

“The day it goes into effect, it will disastrously make every Texan less safe by eroding fundamental community trust with law enforcement,” he said.

In late November, at a Houston-area town hall about the new law, Cesar Espinosa, executive director of the immigrant-led civil rights organization FIEL, said their offices had been inundated with calls.

“We want to remind the community to remain calm,” he said. “Although they are bad laws, they have yet to be implemented. At this point we also have questions about how and if they may be even be able to be implemented.”

CNN’s Ray Sanchez, Michael Williams, Nikki Carvajal and Priscilla Alvarez contributed to this report, which was written by Sanchez.