Construction on a new White House ballroom may proceed after the Supreme Court on Monday rejected a challenge seeking to halt the project. The court, in a 5-4 decision, ruled that the National Trust for Historic Preservation does not have legal standing to bring the lawsuit against the construction, which is slated to cost at least $400 million.

An unsigned majority opinion stated that the court was not ruling on the legality of the East Wing project itself, nor on whether President Trump has the authority to proceed without congressional approval. "We conclude only that, based on the submissions before us, the government is likely to prevail in showing that the Trust lacks … standing to challenge the project in federal court," the opinion read.

However, Chief Justice John Roberts joined the court's three liberal justices in dissent, asserting that the construction is "likely unlawful." Construction on the ballroom has reportedly been underway for nearly a year.

Construction workers stand at the site of the planned White House ballroom.