President Donald J. Trump and Gov. Greg Abbott. Credit: Bob Daemmrich for The Texas Tribune

The Trump administration has officially entered the courtroom battle over Senate Bill 4, Texas’ immigration-enforcement bill.

On Friday, attorneys for the U.S. Department of Justice filed a statement of interest in the federal court case, which was filed last month in San Antonio just one day after Gov. Greg Abbott signed the controversial measure into law.

Known as the “sanctuary cities” bill, the legislation allows local law enforcement officers to question the immigration status of people they legally detain or arrest. It also punishes local government department heads and elected officials who don’t cooperate with federal immigration agents by turning over immigrants subject to possible deportation after the federal government issues what are commonly known as detainers.

Opponents of the measure, which include Houston, Austin, San Antonio, Webb County’s El Cenizo and Maverick and El Paso counties, argue in court filings that the law violates several provisions of the U.S. Constitution, including guarantees of equal protection and freedom of speech. The opponents also argue that the law violates the Constitution’s supremacy clause, which states that federal law — including statutes dealing with immigration enforcement — is “wholly dedicated to the federal government and may not be usurped by the states.”

In its filing, the U.S. Department of Justice argues the bill is constitutional and that the state law is not preempted by federal immigration law. The administration claims that the 10th Amendment guarantees to states the right to craft their own legislation to a certain degree, and that SB 4 is valid.

“The 10th Amendment limits the federal government’s authority to direct state and local officers to take particular actions; it does not limit the prerogatives of the states to provide direction to their own officials. To the contrary, the 10th Amendment expressly reserves right for the states,” the filing states.

“It’s reassuring to know that the Trump administration believes in upholding the Constitution and defending the rule of law, and I’m grateful for the DOJ’s assistance in helping my office defend the lawful Senate Bill 4,” Texas Attorney General Ken Paxton said in a news release.

In its filing, the department also addressed claims that detainers aren’t enforceable because they are merely requests and not actual court orders, as some SB 4 opponents have claimed.

“But as all parties must concede, ICE has issued a policy under which it only issues detainers when there is probable cause on the face of the detainer to arrest an individual on the basis that he is a removable alien, and the detainer is accompanied by an administrative warrant,” the filing states.

U.S. District Judge Orlando Garcia has scheduled a June 26 hearing to consider plaintiffs’ request for a preliminary injunction to stop SB 4 from going into effect as the court case plays out.

Julián Aguilar reports on politics and border affairs from the Texas-Mexico border. His focuses include immigration reform and enforcement, voter ID, international trade, border security, and the drug...