An Iowa bill that was signed into law by Republican Governor Kim Reynolds in April allowing state authorities to arrest and deport some illegal immigrants was blocked by a federal judge, who ruled on Monday that the policy is unconstitutional.

U.S. District Judge Stephen Locher, who was appointed by President Joe Biden, wrote that Iowa’s “illegal reentry” law violates the Supremacy Clause of the Constitution and interferes with the federal government’s authority to enforce immigration laws, the Des Moines Register reported. The Department of Justice sued Iowa over the law last month, arguing that the state was “disregard[ing] the U.S. Constitution and settled Supreme Court precedent.”

The law, which was passed as Senate File 2340, allows state authorities to arrest and deport illegal immigrants who had previously been removed from the U.S. or denied entry into the country. It was set to take effect on July 1.

“As a matter of politics, the new legislation might be defensible. As a matter of constitutional law, it is not,” Locher wrote. “Under binding Supreme Court precedent, Senate File 2340 is preempted in its entirety by federal law and thus is invalid under the Supremacy Clause.”

Locher pointed to a 2012 Supreme Court ruling on an Arizona law that allowed state authorities to stop and detain people suspected of illegally crossing the border. The Supreme Court ruled 5-3 — with Justices Anthony Kennedy and John Roberts joining three liberal justices — that the Arizona immigration law interfered with federal government enforcement of laws already on the books. Justice Antonin Scalia argued that the Arizona law did not conflict with federal law and even worked to better enforce federal law.

Under Iowa’s law, illegal immigrants could face up to 10 years in prison for illegally reentering the U.S. if they were arrested for committing a separate felony. A judge would also be required to submit an order for deportation of an illegal immigrant convicted of unlawfully entering the U.S. Reynolds said in April that the state law was necessary because President Joe Biden “has failed to enforce our nation’s immigration laws, putting the protection and safety of Iowans at risk.”

Reynolds and Iowa Republican Attorney General Brenna Bird have vowed to appeal Judge Locher’s ruling, according to the Des Moines Register.

“I am disappointed in today’s court decision that blocks Iowa from stopping illegal reentry and keeping our communities safe,” Bird said. “Since Biden refuses to secure our borders, he has left states with no choice but to do the job for him.”

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The Iowa immigration law is similar to legislation passed in other GOP-controlled states such as Texas and Georgia. Texas’ law authorizing state authorities to prosecute migrants for illegally crossing the southern border has also been blocked.

As Reynolds argued in Iowa, Texas Republican Governor Greg Abbott and Attorney General Ken Paxton said that the Biden administration is failing to address illegal immigration. Paxton added that the state has a constitutional duty to protect its citizens “from violent transnational cartels that flood the State with fentanyl, weapons, and all manner of brutality.”