The U.S. Supreme Court has blocked enforcement of a key provision of a controversial Florida law that criminalized entry into the state by undocumented immigrants, delivering a setback to Governor Ron DeSantis's immigration policy.

In a succinct, one-sentence order issued Wednesday, the high court upheld a lower court's ruling without elaboration or recorded dissents. The provision in question had imposed mandatory prison sentences for undocumented individuals crossing state lines into Florida.

The dispute stems from a law enacted by Governor DeSantis in February, which quickly garnered national attention following an incident in April involving Juan Carlos Lopez-Garcia, a U.S.-born citizen arrested by Florida Highway Patrol while crossing from Georgia. Lopez-Garcia, wrongly detained for 24 hours, became a central figure highlighting concerns raised by immigration advocacy groups.

The plaintiffs, including immigrant rights organizations, argued that the Florida statute directly conflicted with established federal immigration law. They contended that under longstanding Supreme Court precedent, immigration regulation is a federal domain, preempting any conflicting state laws.

Florida officials defended the measure as necessary to mitigate what they termed the "evil effects of immigration," asserting that state law complemented, rather than contradicted, federal immigration statutes.

Nevertheless, the Supreme Court has consistently ruled that federal law supersedes state laws in immigration matters. Similar statutes criminalizing immigration at the state level have been previously blocked by federal courts in Oklahoma, Iowa, and Idaho, with courts repeatedly affirming that such state measures infringe upon the federal government's exclusive authority to regulate immigration.

Most recently, in 2024, the conservative Fifth Circuit Court of Appeals halted a similar Texas law, underscoring the ongoing judicial consensus against state-level immigration enforcement.