Judge Promptly Blocks Work on Trump’s Triumphal Arch After It’s Approved The judge acted swiftly after a federal planning board led by the president’s allies approved Trump’s 250-foot arch project on Thursday.

A federal judge on Thursday night promptly blocked construction of President Trump’s 250-foot triumphal arch near the entrance of Arlington National Cemetery after a Trump-friendly panel approved it.

The ruling temporarily stalled progress on one of the president’s favorite projects, which Democrats have threatened to kill when they take control of Congress in January.

The federal panel’s decision to go ahead with Mr. Trump’s plan would have allowed construction to begin as soon as Friday morning. But the ruling by Judge Tanya S. Chutkan halted construction for 14 days while legal challenges make their way through the court system.

In a 33-page opinion, Judge Chutkan said the arch required congressional approval and that its construction could prove costly to both Virginia and the District of Columbia while disrupting traffic at the Arlington cemetery, one of the region’s most-visited sites.

The case before Judge Chutkan combined two lawsuits brought by a group of veterans and another brought jointly by the District of Columbia and the Commonwealth of Virginia. The lawsuits argued that planning for the arch skipped environmental and historical reviews and required “specific congressional authorization” that the Trump administration did not seek.

Administration officials contended that the project was needed to keep the nation’s capital safe from drone attacks, although the national security aspect was not part of the original proposal. Judge Chutkan wrote that the claims were curiously timed.

“These recent and unsupported attestations of security aspects of a structure that has been extensively discussed over the last year appear nowhere in the planning documents on which the project was reviewed and approved,” she wrote.

The panel’s 8-to-4 vote to give final approval to the triumphal arch came soon after the Republicans’ historic defeat in midterm elections on Tuesday. Mr. Trump fixated on his legacy projects, including the arch and White House ballroom, throughout the campaign.

About 130 people signed up to testify Thursday during a marathon session before the vote by the commission, which has received almost uniformly negative responses about the project.

“The Great Gatsby party is over,” said Representative Jared Huffman, Democrat of California, before the National Capital Planning Commission met for the vote on the arch Thursday. “The arch is an illegal project. It’s a monstrosity. It’s a slap in the face to veterans and to the history and the aesthetics of this sacred place. It’s unthinkable that this would be allowed to proceed.”Many argued that the arch would detract from the solemn atmosphere of the nearby Arlington National Cemetery.

“The arch’s brutal and insensitive size detracts from the modest reflection of love, remembrance and selflessness the existing memorials encourage,” testified Joseph Zengerle, a West Point graduate and Vietnam veteran. “And the arch would forever bring to mind the evident rationale for its construction: President Trump’s exercise of his desire to memorialize himself.”Despite the public outcry, Mark Paoletta, the chairman of the commission, made it clear that the panel planned to move forward.

“President Trump’s historic vision for a monumental arch at Memorial Circle would complete a project over a century in the making, and honor our nation and her veterans, and provide the sacred ground of Arlington National Cemetery with the monumental gateway it deserves,” Mr. Paoletta said. “It would also represent a generational security opportunity to protect our nation’s capital.”When some on the board asked to delay the vote, Stuart Levenbach, the panel’s vice chairman who was appointed by Mr. Trump, emphasized the need to act immediately.

“As I understand it, the project proponent is under a time constraint and wants the decision today,” he said.

The commission’s vote marked the final review step for the project. The administration had said in court that construction could start the same day.

A group of veterans in February brought an initial suit to block the arch, saying that their experience of the views and the solemnity at Arlington National Cemetery would be degraded by the towering monument. Last week, a separate suit brought by the District of Columbia and the Commonwealth of Virginia introduced more concrete harms: They said the project would clog traffic, disrupt emergency responses, threaten the environment and require them to spend resources addressing those problems.

Lawyers representing D.C. and Virginia argued that the arch violated a federal law limiting the height of buildings in Washington to 130 feet. The Federal Aviation Administration has also studied whether the arch would interfere with flights in and out of Ronald Reagan National Airport.

Adopting an argument used in litigation over the White House ballroom, Mr. Trump has said this year that the arch would double as a national security fixture, housing swarms of drones and snipers’ nests.

Judges considering a challenge to the ballroom had been hesitant to interfere with construction, particularly beneath the new structure, acknowledging that facilities in the White House campus might require extraordinary security features. Mr. Trump has been able to bring the ballroom close to completion despite court orders requiring him to stop building, largely because of those national security claims.

Luke Broadwater covers the White House for The Times.

Zach Montague is a Times reporter covering the federal courts, including the legal disputes over the Trump administration’s agenda.

Emily Badger writes about cities and urban policy for The Times from Washington. She’s particularly interested in housing, transportation and inequality — and how they’re all connected.