The Fulton County District Attorney, Fani Willis, is hankering for a constitutional crisis. That is our takeaway from the elevating chances that she is going to try to throw the 45th president in the dock while he is the Republican nominee for president or even — if he wins — after he is reinstalled as the commander in chief. It is difficult to conceive of an outcome more conflicted with  the Framers’ designs for the presidency.

Ms. Willis is pushing for an August beginning for her racketeering case against Mr. Trump and 14 others accused of conspiring to overthrow the 2020 election. Such capacious conspiracy cases bring to mind how the author Henry James described the novels of his 19th century predecessors — “loose, baggy monsters.” Trying 15 defendants at once is a daunting proposition, no matter how blind justice turns out to be.

The DA knows this because this is not her first racketeering rodeo. She brought one such sprawling case against a collection of allegedly crooked teachers at Atlanta. That resulted in the longest trial in the history of Georgia, one worthy of Dickens. It was eight months long. As our A.R. Hoffman reports, another racketeering case, against the rapper Young Thug, could last longer. An August trial for Mr. Trump might not conclude by the time ballots are cast. 

That possibility — call it an inevitability — was marked in court by Mr. Trump’s attorney, Steven Sadow. He called the scenario, in which Mr. Trump is both the Republican nominee and a state criminal defendant, the “most effective election interference in the history of the United States.” Mr. Trump, he added, would not be “able to campaign for the presidency because he is in some form or fashion in a courtroom defending himself.”

Mr. Sadow proposes that if Mr. Trump wins the election, his  trial should be delayed until 2029. The question has not been briefed, but Mr. Trump’s argument is no constitutional joke. The parchment vests in the president personally the “executive power” and ordains that he takes care that the laws be faithfully executed. “With great responsibility comes great power,” as Stan Lee put it in his immortal aphorism.

It is difficult to envision one discharging those duties discharged from the witness stand. Thomas Jefferson put this in a letter — warning that the “several courts” could “bandy” the president “from pillar to post, keep him constantly trudging from north to south & east to west, and withdraw him entirely from his constitutional duties.” The Supremacy Clause could hand Mr. Trump a shield against Ms. Willis’s Georgian impositions.

The federalism question — can a president be tried in state court  — summoned by Ms. Willis’s prosecution appears unlikely to take up permanent residence at Fulton County. Yet it goes to the very pith of the presidency and the quick of the Constitution. It could well land on the Supreme Court docket, the address for discerning the Founders’ designs. Could the Nine conclude that Ms. Willis has bitten off more than the Constitution allows her to chew? 

More broadly still, the Democrats’ pursuit of Mr. Trump smacks of a certain cockiness that is, under the circumstances, inapt. He must, after all, be at this stage of things presumed innocent in Georgia, New York, Florida, and the Columbia District. Our concern here is not so much the fate of Mr. Trump or Ms. Willis but of due process. It is no small thing that this defendant could be gaining his campaign for the highest office in the land while being in the dock.