As debate intensifies over a proposed 250-foot triumphal arch honoring Donald Trump, a fundamental constitutional question remains: Does Congress have the authority to approve such a monument? At the center of the president's argument is a century-old law that Trump and his allies may invoke to justify the project, though critics dismiss the proposed monument as a vanity project.

The central question is whether a 1925 law gives Trump the authority to build the arch, despite more recent language requiring congressional approval for new monuments in the nation's capital. The administration argues that Congress already approved the project under the 1925 law, citing an unrealized plan by the Arlington Memorial Bridge Commission from the1920s, which proposed two tall, narrow columns spaced far apart at the western end of a new bridge across the Potomac River. According to the administration, the proposed arch follows the original vision of that plan. The stakes of that interpretation are considerable: if the 1925 law is deemed sufficient, the arch could proceed without a new act of Congress; if not, the later approval requirement would stand in the way.

The argument has drawn open scorn. "The idea that this proposal is somehow justified by what happened in the 1920s and '30s with the proposals for the bridge — not to be blunt about it, but it just doesn't pass the laugh test," David Maloney, the District of Columbia's state historic preservation officer, told the National Park Service in a recorded meeting in September, as reported by The New York Times.

According to USA Today, the monument's ambition extends well beyond its height. The structure would stand twice as tall as the nearby 99-foot Lincoln Memorial, with two gilded eagles above the arch's legs and a gilded winged figure holding a torch at its top. The arch would rise across the Potomac River, appearing to face the Lincoln Memorial. Plans call for an observation deck overlooking the surrounding area, as well as a surrounding plaza, granite pavers, landscaping, a stone seat wall, and pedestrian crosswalks with lighting. The design's scale helps explain why it has collided with the capital's modern approval process, which gives Congress the final word on new monuments in Washington.

Critics object to both the monument's size and its location. The arch is slated to rise near Arlington National Cemetery, and numerous veteran groups, local advocacy organizations, and historic preservationists have voiced opposition, urging Trump to reduce the planned height or select a different site altogether.

Trump and his allies are pushing back. "The empty Memorial Traffic Circle built in 1940 does not complete the grand design authorized and envisioned by the Arlington Memorial Bridge Commission and by Congress as enacted in the 1925 law," Paoletta wrote on X this week. "It is a disgrace to our nation and her noble veterans."

Where the dispute goes next will likely run through the federal review process itself: the National Park Service, the agency before which Maloney's critical remarks were recorded in September, has already become a forum for the opposing arguments over the 1925 law.