The US Department of Justice (DOJ) sued Texas and Governor Greg Abbott in his official capacity on Wednesday over a state law that criminalizes illegal entry into the border state from anywhere but a port of entry, exerting state jurisdiction over what is usually a federal matter. The case is in the US District Court for the Western District of Texas Austin Division.

Last month, Abbott signed SB 4. The law creates a misdemeanor offense for violation of the statute and a felony crime for multiple offenses. It also empowers state magistrate judges to hear immigration cases and issue removal orders, in addition to giving law enforcement the responsibility of ensuring compliance with the law.

The complaint filed asserts that the Texas law is preempted by federal law. It avers that the law “unconstitutionally intrudes on the federal government’s exclusive authority to regulate the entry and removal of noncitizens and therefore is field preempted.” The Supremacy Clause of the US Constitution states:

This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.

In support of its claim, the DOJ cites several provisions of federal law that already regulate this area, and alleges that the law violates the Foreign Commerce Clause under Article I Section 8 of the Constitution. This clause gives Congress the power to regulate commerce with foreign nations. Lastly, the complaint asks the court to declare that the law violates the Supremacy Clause and the Foreign Commerce Clause and to permanently enjoin Texas from enforcing the law.

Addressing the lawsuit, Associate Attorney General Vanita Gupta stated:

SB 4 is clearly unconstitutional. Under the Supremacy Clause of the Constitution and longstanding Supreme Court precedent, states cannot adopt immigration laws that interfere with the framework enacted by Congress. The Justice Department will continue to fulfil its responsibility to uphold the Constitution and enforce federal law.

This is not the only litigation involving Texas and the federal government over immigration. Currently, there is a lawsuit over Texas’ wire fence at the US-Mexico border and the federal government’s attempts to remove the fence.