The unsigned decision, issued with Justice Ketanji Brown Jackson noting she would have denied the government's request for emergency relief, reverses a preliminary injunction from U.S. District Judge Kathleen Cardone that had barred construction of border barriers and related activities in the Big Bend sector. That sector covers more than 500 miles of the southern border and includes Big Bend National Park.

In its five-page order, the court said the lower court's injunction "impedes the Government from advancing its 'compelling interests' in border security and integrity." The justices also pointed to a 1996 immigration law that allows the Homeland Security secretary to waive environmental and other conservation requirements, writing that Congress's enactment "reflects a clear preference for expeditious border construction over the very harms respondents assert."

The Trump administration had asked the high court last month to intervene, arguing that the halt ordered by Cardone frustrated its ability to combat illegal border crossings. Solicitor General D. John Sauer warned that stopping construction would cause "disruption of the government's ability to secure a quarter of the southern border against cartel incursions, drug trafficking, and illegal entry" and create "a massive vulnerability in border protection."

But the challengers — an environmental nonprofit, a professional riverboat guide and a religious organization — argued that resuming construction would permanently alter an "irreplaceable landscape" encompassing Big Bend National Park, Big Bend Ranch State Park and nearly 200 miles of the Rio Grande Wild and Scenic River corridor.

"Once habitat is destroyed, vegetation cleared, historic resources damaged, livelihoods and private property destroyed, and wilderness landscapes fragmented by roads, barriers, and associated infrastructure, no final judgment can restore the status quo," their lawyers wrote in a Supreme Court filing.

The dispute centers on three waivers issued by Homeland Security secretaries Kristi Noem and Markwayne Mullin beginning in February, invoking the 1996 law to bypass federal environmental and historical preservation reviews. The plaintiffs sued to stop construction of new 30-foot bollard walls and other infrastructure, saying the waivers would "authorize massive projects that would cleave through the Chihuahuan Desert, sever public and wildlife access to iconic sections of the Rio Grande, and mark one of the final—and most consequential—steps towards completing 'the Wall.'"

Cardone found that the Homeland Security secretary exceeded his authority in issuing the waivers. The government and challengers also disputed whether the Big Bend sector qualifies as an area of "high illegal entry." The government said officers apprehended more than 89,000 people there between 2021 and 2025, while the plaintiffs countered that Big Bend ranks last among the six southern border sectors for apprehensions, with annual figures ranging from 0.3% to 2.2% of the border-wide total despite covering more than 25% of the U.S.-Mexico border.

The project has drawn opposition from Republican and Democratic lawmakers, cattle ranchers and local law enforcement in Texas. In August, photos and videos on social media showed bulldozers arriving at Big Bend National Park, prompting Customs and Border Protection Commissioner Rodney Scott to pause construction inside the park until the end of September. Scott has said the 30-foot wall will not cut through the national park, but other infrastructure would, including more than 200 miles of patrol roads and roughly 17 miles of a vehicle-barrier system, according to CBP.

Construction of a 47-mile stretch of wall in Hudspeth County, part of the Big Bend region, began in September. The Supreme Court's action Monday means work can resume across the sector as the litigation continues.