A group of lawmakers has cautioned the Trump administration that proceeding with construction of a proposed 250-foot United States Triumphal Arch in Washington without congressional authorization could lead to legal consequences, including fines and criminal prosecution. The warning was issued in a letter dated Monday, addressed to Interior Secretary Doug Burgum and officials with the National Park Service.

The letter, signed by Senator Angus King of Maine, an independent who caucuses with Democrats, Representative Jared Huffman of California, the top Democrat on the House Natural Resources Committee, and other members, asserts that building the arch would violate at least three federal laws. Among these are provisions that prohibit the use of appropriated funds for unapproved purposes, the Commemorative Works Act which governs memorials on federal land in Washington, a 1912 statute requiring express congressional authority before erecting structures on federal land in the capital, and the Height of Buildings Act, which generally limits building height to 160 feet. The proposed arch’s height would exceed this limit.

“This project is stone-cold illegal,” King said in an interview, calling it one of the clearest legal violations he had seen in his five-decade career. The letter warns that officials who knowingly violate these laws could face suspension without pay, removal from office, and even criminal penalties.

In addition to congressional opposition, a group of Vietnam War veterans has sued to halt the project, contending that the arch would obstruct the sightline between the Lincoln Memorial and Arlington National Cemetery and lack authorized approval from Congress.

Trump administration officials dispute these claims, arguing that the Height of Buildings Act does not apply to the arch. They cite congressional acts from the 1920s related to the Arlington Memorial Bridge — near the intended site of the arch — as granting implicit authority for its construction. This justification has been met with skepticism by lawmakers. Huffman described the administration’s legal rationale as “laughable” and “so specious on its face” that it is unlikely to prevail in court.

While the courts are one avenue to challenge the project, Huffman noted that if Democrats regain control of the House following the midterm elections, increased oversight could also be employed to impede the effort. “We’re putting people on notice,” he said, emphasizing potential personal liability for those involved in carrying out unauthorized directives.

Responding to the legal concerns, Interior Department spokeswoman Katie Martin maintained that the administration is honoring longstanding congressional intent. She referenced the 1902 Senate McMillan Commission’s recommendation to create “a concourse suited to memorial treatment” at the western end of Memorial Bridge, as well as the 1924 Arlington Memorial Bridge Commission’s call for a plaza with architectural features complementing the Lincoln Memorial.

“Great nations build beautiful structures and works of art that cultivate national pride and love of country,” Martin said. She added that Secretary Burgum is enthusiastic about championing the Triumphal Arch project, which the administration believes will inspire pride among all Americans.