The US Supreme Court on Wednesday declined to allow Florida to enforce a state law criminalizing entry into the state by undocumented immigrants, leaving in place a federal judge’s preliminary injunction that blocked the measure while legal challenges proceed.

The law, SB 4-C, which was enacted in February, creates state crimes for undocumented immigrants who enter or re-enter the state, imposing mandatory minimum prison sentences ranging from nine months to five years depending on prior convictions, while requiring detention without bail and mandating that those convicted of capital felonies receive the death penalty, with law enforcement required to notify federal immigration authorities of all arrests under the statute.

In April, several civil rights and immigration advocacy groups filed suit to block enforcement of the law, with the American Civil Liberties Union (ACLU) decrying it as a “sweeping and unlawful expansion of state power under the guise of immigration enforcement.” In their complaint, the organizations, representing undocumented individuals as plaintiffs, argued the law violates federal supremacy over immigration by creating a parallel state system that allows Florida officials to arrest, prosecute and imprison immigrants for entering or re-entering the state outside federal oversight, with plaintiffs contending the measure conflicts with comprehensive federal immigration law and impermissibly regulates interstate commerce.

Later that month, the US District Court for the Southern District of Florida granted the injunction, finding the plaintiffs had demonstrated a likelihood of success on the merits, reasoning that the law is likely preempted by federal law. Florida appealed to the 11th US Circuit Court of Appeals, which refused to stay the injunction.

Florida then appealed to the nation’s highest court, arguing the district court had wrongly found the law was preempted by federal immigration law, and that states have sovereignty to criminalize illegal entry and re-entry within their own borders.

The Supreme Court denied the application without providing commentary on its rationale. With the ruling, the block on Senate Bill 4-C will continue until the merits of the plaintiffs’ claims have been considered.

The executive director of ACLU Florida, Bacardi Jackson, celebrated the court’s ruling, saying it “affirms what the Constitution demands—that immigration enforcement is a federal matter and that no one should be stripped of their liberty without due process.”