President Trump’s marshaling of the Constitution’s Supremacy Clause, in a filing Friday morning, to persuade Judge Scott McAfee to dismiss two more of the charges handed up by District Attorney Fani Willis could deliver the embattled Atlanta prosecutor another loss at a moment when her case can ill afford it. 

The 45th president has already enjoyed success whittling down Ms. Willis’s sprawling racketeering indictment charging him and several co-defendants with election interference. In March, Judge McAfee dismissed six of the 13 counts against him after Mr. Trump argued that they were unconstitutionally vague. Now, if the judge is persuaded again, the indictment could shrink even further. 

Mr. Trump is working to slim down the roster of charges he faces even as his case to disqualify Ms. Willis from the prosecution team will soon receive a hearing before the Georgia Court of Appeals. He contends that her romantic relationship with her former special prosecutor, Nathan Wade, as well as her comments at a Black church accusing her defendants of playing the race card, warrant her removal from the case.

On a separate track, Mr. Trump, who is facing similar charges brought by Special Counsel Jack Smith, argues that the district attorney has overstepped her authority by charging him with crimes that can only be decided by federal tribunals. The Supremacy Clause ordains:

“This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any thing in the Constitution or Laws of any State to the Contrary notwithstanding.”

When federal and state law clash, it is the federal one that is to be honored. As Mr. Trump puts it, a “state may not encroach on exclusive federal jurisdiction.” He calls this the “basic operational precept of the Supremacy Clause,” and maintains that in this instance Georgia’s “general criminal laws have no application.”

The charges at issue are “conspiracy to commit filing false documents” and “filing false documents” to the United States District Court for the Northern District of Georgia. Mr. Trump explains that when “matters are exclusively within the federal realm, the federal sovereign alone has the authority and jurisdiction to decide whether and how to criminalize that conduct.”

A seminal Supremacy Clause case, In re Loney, dates from 1890. Justice Horace Grey explains that a “witness who gives his testimony, pursuant to the Constitution and laws of the United States in a case pending in a court or other judicial tribunal of the United States … is accountable for the truth of his testimony to the United States only.” He “cannot therefore be punished in the courts of Virginia,” the state where the offense was committed.

Ms. Willis, though, contends that the unusual facts of the case make it an inapt precedent. In re Loney came to the high court via the United States Court of Appeals for the Third Circuit. A Virginian, Wilson Loney, gave testimony with respect of a contested election of the United States House of Representatives. He was convicted of perjury by a state court, but appealed to the Third Circuit via a writ of habeas corpus. They released him, and the high court affirmed. 

The Supreme Court explained that Loney was held “in custody, in violation of the Constitution and laws of the United States, for an act done in pursuance of those laws, by testifying in the case of a contested election of a member of Congress, law and justice required that he should be discharged.” Mr. Trump contends that what was good for Loney long ago is just for him today. 

Ms. Willis argues that Mr. Trump’s attorneys are reaching too far. She claims that Loney’s crime was perjury and that it occurred with respect to an apex area of federal interest — the election of members to the House. Mr. Trump retorts that the accusation that he submitted false claims to a federal court is not that different from perjury, and that he was running for president. 

That this motion to dismiss is even being heard by Judge McAfee, who faces a primary election on Tuesday, is a product of his ruling that the case move forward even as Ms. Willis’s role in it is adjudicated on appeal. Even if she manages to keep her perch, though, she could find herself presenting fewer charges to a jury than she had intended.