AUSTIN, Texas — Texas’ plans to arrest migrants who enter the U.S. illegally and order them to leave the country is headed to the Supreme Court in a legal showdown over the federal government’s authority over immigration.

An order issued Monday by Justice Samuel Alito puts the new Texas law on hold for at least next week while the high court considers what opponents have called the most dramatic attempt by a state to police immigration since an Arizona law more than a decade ago.

The law, known as Senate Bill 4, had been set to take effect Saturday under a decision by the conservative-leaning 5th U.S. Circuit Court of Appeals. Alito’s order pushed that date back until March 13 and came just hours after the Justice Department asked the Supreme Court to intervene.

“Make no mistake: S.B. 4 bypasses federal immigration authority and threatens the integrity of our nation’s constitution and laws,” a coalition of groups that sued over the law, including the American Civil Liberties Union, said in a statement.

Republican Gov. Greg Abbott signed the law in December as part of a series of escalating measures on the border that have tested the boundaries of how far a state can go to keep migrants from entering the country.

The law would allow state officers to arrest people suspected of entering the country illegally. People who are arrested could then agree to a Texas judge’s order to leave the country or face a misdemeanor charge for entering the U.S. illegally. Migrants who don’t leave after being ordered to do so could be arrested again and charged with a more serious felony.

The Justice Department told the Supreme Court that the law would profoundly alter “the status quo that has existed between the United States and the States in the context of immigration for almost 150 years.” It went on to argue that the law would have “significant and immediate adverse effects” on the country’s relationship with Mexico and “create chaos” in enforcing federal immigration laws in Texas.

The federal government cited a 2012 Supreme Court ruling on an Arizona law that would have allowed police to arrest people for federal immigration violations, often referred to by opponents as the “show me your papers” bill. The divided high court found that the impasse in Washington over immigration reform did not justify state intrusion.

The Supreme Court gave Texas until March 11 to respond.

In a statement Monday, the Texas Attorney General’s Office said the state’s law mirrored federal law and “was adopted to address the ongoing crisis at the southern border, which hurts Texans more than anyone else.”

The federal government’s emergency request to the Supreme Court came after a federal appeals court over the weekend stayed U.S. District Judge David Ezra’s sweeping rejection of the law.

In a 114-page ruling Thursday, Ezra rebuked Texas’ immigration enforcement and brushed off claims by Republicans about an ongoing “invasion” along the southern border due to record-high illegal crossings.

Ezra added that the law violates the U.S. Constitution’s supremacy clause, conflicts with federal immigration law and could get in the way of U.S. foreign relations and treaty obligations.

According to Ezra’s ruling, allowing Texas to supersede federal law due to an “invasion” would “amount to nullification of federal law and authority – a notion that is antithetical to the Constitution and has been unequivocally rejected by federal courts since the Civil War.”

Republicans who back the law have said it would not target immigrants already living in the U.S. because the two-year statute of limitations on the illegal entry charge would be enforced only along the state’s border with Mexico.

Texas has been arresting migrants for years under a different program that is based on criminal trespass arrests.

Though Ezra said some might sympathize with Texas officials’ concerns about immigration enforcement by the federal government, he said that was not enough to excuse a violation of the U.S. Constitution.

The battle over the Texas immigration law is one of multiple legal disputes between Texas officials and the Biden administration over how far the state can go to patrol the Texas-Mexico border and prevent illegal border crossings.

Several Republican governors have backed Abbott’s efforts, saying the federal government is not doing enough to enforce existing immigration laws.

Some of Abbott’s attempts to impede illegal border crossings have included a floating barrier in the Rio Grande – which Ezra previously blocked and is part of an ongoing legal battle– and placing razor wire along the state’s boundary with Mexico. State guard officers have also blocked U.S. Border Patrol agents from accessing a riverfront park in Eagle Pass that was previously used by federal agents to process migrants.