The tables have turned. Had everything gone according to plan, Donald Trump would be on trial right now in South Florida for hoarding classified documents at his Mar-a-Lago ocean estate after leaving the White House. The politician, still licking his wounds from his New York conviction, would be desperately fighting to stave off a humiliating distinction: becoming the first former president to be branded a two-time felon. Instead, a very different trial of sorts will be underway this Friday at a tiny federal courthouse in the sunny beach city of Fort Pierce—one that will awkwardly put the Department of Justice...