In the latest showdown over immigration law, the U.S. Department of Justice has threatened to sue the state of Texas if it doesn’t retract a new law that would allow state and local police to arrest migrants who enter the country illegally.

The law, known as Senate Bill 4, was signed by Texas Gov. Greg Abbott earlier this month and is set to go into effect in March.

In a letter dated Thursday, the DOJ gave Abbott until Jan. 3 to withdraw the state’s intention to enforce the law or face a “lawsuit to enforce the supremacy of federal law and to enjoin the operation of S.B. 4.” The letter cites a 2012 U.S. Supreme Court case over Arizona’s “show me your papers” law, which ruled that the law was unconstitutional and stated that the federal government, not individual states, set immigration policy.