The U.S. Department of Justice on Wednesday sued Texas and Gov. Greg Abbott to block what the agency is calling an “unconstitutional” immigration law that would make it legal for Texas state judges to deport foreign-born people to Mexico despite their nationality.

The Texas law, Senate Bill 4, violates the Constitution’s supremacy and foreign commerce clauses, according to the lawsuit. Those clauses give the federal government authority to regulate immigration and manage international borders, superseding state authority. Signed December 2023 by Abbott, the law was expected to take effect on March 5.

“SB 4 is clearly unconstitutional,” said Associate Attorney General Vanita Gupta in a statement. “States cannot adopt immigration laws that interfere with the framework enacted by Congress.”

The lawsuit was filed on behalf of the United States, including the DOJ, the Department of Homeland Security and the Department of State.

If enacted, Texas’ law would create new state crimes, ranging from misdemeanor to felony, in an attempt to regulate immigration. These charges include: illegal entry from a foreign nation, illegal reentry by certain noncitizens and refusal to comply with an order to leave the country. Penalties for these offenses include a fine of up to $2,000 and imprisonment for up to 180 days.

Judges could also immediately deport arrested undocumented people “in lieu of continuing the prosecution.”

Domingo Garcia, president of the League of United Latin American Citizens (LULAC), agrees with the DOJ’s justification in suing Texas over SB 4.

Garcia was surprised Abbott seemed to overlook the supremacy clause, condemning the Texas Republican for “spending taxpayers’ dollars on political stunts like this that will not solve the political problems and will not solve the humanitarian crisis on the border.”

Federal penalties already exist for noncitizens who enter the country and the U.S. has measures in place to remove those without authorization. Officials cited precedent established in the Supreme Court case Arizona v. United States, which asserted in 2012 that the removal of noncitizens from the state was an issue of “foreign relations and must be made with one voice.”

SB 4 does not allow for defenses protecting refugees from removal, meaning that noncitizens eligible for federal relief would nonetheless still be deported due to Texas state law, prosecutors said.

The legislation also does not include exceptions for reentry into the country, potentially prohibiting noncitizens from entering even if they have permission from federal agencies like Homeland Security, officials said.

“In this way, Texas is attempting to undertake its own removals without adhering to the removal scheme Congress devised,” the complaint reads.

Prosecutors said SB 4 “does not accommodate” U.S. treaty obligations, such as the Convention Against Torture, which prohibits deporting noncitizens to a country where they will they will likely be harmed. The international agreement under the United Nations was signed in 1985 and protects against cruel, inhuman or degrading treatment.

The complaint said forcing non-Mexican nationals to return to Mexico could damage diplomatic relations with the neighboring country and interfere with its sovereign right to determine who enters their territory.

Mexican President Andres Manuel Lopez Obrador has publicly denounced the Texas law. The Mexican government in November called the legislation an “anti-immigrant measure that aims to stop the flow of migrants by criminalizing them.”

In addition to the DOJ lawsuit, immigrant rights organizations have also sued Texas over SB 4, with advocates calling the law “extreme.”

“LULAC calls for a reevaluation of Governor Abbott’s actions, emphasizing the need to uphold the Constitution and work collaboratively to address the complex immigration issues,” said Lydia Guzman, the LULAC national immigration chair, in a statement. “We remain committed to protecting the rights of the Hispanic community and ensuring that justice prevails for all.”