Texas lodged a preemptive lawsuit Monday against local officials considered hostile to the state’s new anti-sanctuary cities law, the first salvo in an expected legal fight over the controversial measure.

State Attorney General Ken Paxton said the federal lawsuit, filed in the U.S. District Court for the Western District of Texas, is necessary to protect the law from challenges by liberal municipal officials and immigrant rights groups.

“[The law] is constitutional, lawful and a vital step in securing our borders,” Paxton said in a statement. “Unfortunately, some municipalities and law enforcement agencies are unwilling to cooperate with the federal government and claim that SB 4 is unconstitutional.”

The Texas suit names as defendants Travis County Sheriff Sally Hernandez, Austin Mayor Steve Adler, all of Austin’s City Council members, and the Mexican American Legal Defense and Educational Fund. State lawyers are asking the federal district court to find that SB 4 does not violate the Fourth Amendment right to protection against unreasonable searches and seizures or the 14th Amendment right to equal protection.

“Governments throughout Texas have a clear duty to continue holding undocumented and suspected criminal aliens pursuant to ICE detainers,” Paxton said. “This is a public safety issue that requires swift resolution.”

Texas GOP Gov. Greg Abbott signed the anti-sanctuary bill, known as SB 4, into law on Sunday during a surprise Facebook Live broadcast. The law is the nation’s first that bans sanctuary jurisdictions and prescribes jail time for police chiefs and county sheriffs who refuse to cooperate with federal immigration authorities. Its most controversial provision allows police officers to inquire about the immigration status of people they detain, including the subjects of traffic stops.

Civil rights groups say the law is unconstitutional and could lead to racial profiling by police. Some Texas law enforcement officials have also publicly opposed the law, arguing that it will force them to dedicate local resources to federal immigration enforcement and drive a wedge between officers and immigrant communities they police.

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