Vietnam War veterans and an architectural historian sued President Trump over his plan to build a 250-foot triumphal arch near Arlington Cemetery's entrance, arguing it violates federal law by bypassing required congressional approval. The federal Commission of Fine Arts approved the design concept on April 16, but multiple additional federal agencies must sign off before construction can begin. The lawsuit hinges on whether the president can unilaterally authorize a major monument project without legislative approval — a legal question that will likely define how much latitude the executive has over new structures in the nation's capital.