The dc-circuit affirmed the district court’s judgment issuing a modified preliminary injunction that prohibits the above-ground physical construction of the proposed 90,000-square-foot ballroom on the former site of the White House East Wing, while expressly allowing below-ground construction of national security facilities and above-ground measures strictly necessary to cover, secure, and protect those facilities. The court held that the National Trust for Historic Preservation likely has associational standing because its member, Professor Alison Hoagland, demonstrated a concrete and imminent aesthetic injury to her professional and personal interests in viewing the White House and President’s Park, which is germane to the organization’s preservation mission. On the merits, the court found the National Trust likely to succeed on its claims that the construction violates 40 U.S.C. § 8106, which requires express congressional authority to erect buildings on federal grounds in the District of Columbia. The court ruled that neither the National Park Service Organic Act (54 U.S.C. § 100101(a)) nor the President’s funding authorization statute (3 U.S.C. § 105(d)) provided such express authority. Specifically, the Organic Act mandates the conservation of historic objects and leaving them unimpaired for future generations, a standard the demolition and replacement of the East Wing violates. Furthermore, Section 105(d) is an appropriation authorization that does not grant independent substantive authority to construct new buildings, particularly when funded by private donations rather than congressional appropriations, and the term “improvement” in that statute does not encompass the construction of a massive new structure replacing an existing wing. The court also rejected the government’s arguments under the Economy Act, noting that an agency cannot contract another agency to perform work it lacks authority to do itself. The practical consequence is that the above-ground construction of the ballroom must cease pending the resolution of the litigation, though security-related underground work and protective measures may proceed. The court vacated its prior administrative stay and stayed its own decision for fourteen days to allow the government to seek review by the Supreme Court.