The Supreme Court’s ruling that former presidents are entitled to “presumptive immunity” for official acts could soon wreak havoc on Fulton County District Attorney Fani Willis’s racketeering prosecution of President Trump — at a juncture when she can ill afford another setback.

The 45th president’s resounding victory at the high court applies to state charges as well as federal ones, even as the pardon power is limited to federal crimes. Now, it is prosecutors who will bear the burden of piercing presidential immunity for official acts.

The newly arduous legal landscape for Special Counsel JackSmith, currently prosecuting Trump in two federal criminal cases, as well as for state prosecutors like Ms. Willis and District Attorney Alvin Bragg, came into focus on Tuesday. Mr. Bragg acceded to Trump’s request that his hush money sentencing be postponed while the effects of the immunity ruling are metabolized by the presiding judge in the case, Juan Merchan. Trump is asking for his conviction to be overturned. 

Ms. Willis’s case against Trump, which doesn’t even have a trial date yet, is already frozen pending a petition to the Georgia Court of Appeals from the former president seeking to disqualify her. That request cites her affair with her former boyfriend and special prosecutor, Nathan Wade. It also alleges that her comments about the case — say, accusing her opponents of “playing the race card”— amount to efforts to poison the jury pool in majority-minority Fulton County, which comprises much of downtown Atlanta

In the wake of Trump v. United States, though, Ms. Willis’s case, which centers on Trump’s alleged efforts to overturn the results in the 2020 election in Georgia, could be in trouble on the merits. At the very least, it appears that extensive litigation to discern official from unofficial acts  is ahead before the trial judge, Scott McAfee. 

Those hearings could mirror the ones that will occur before Judge Tanya Chutkan, to whom the high court remanded the January 6 case. The new teaching of the high court is that “there is no immunity for unofficial acts,” there is “absolute immunity” for acts that come within the core functions of the presidency, and there is presumptive immunity for all official acts. 

The Supreme Court, though, went further. Evidence involving official acts is not only presumptively immune. It also cannot be used to support charges that involve unofficial acts. Justice Amy Coney Barrett broke from her conservative colleagues on this point, writing that the “Constitution does not require blinding juries to the circumstances surrounding conduct for which Presidents can be held liable.” She joined, though, in the final ruling. 

Trump is charged with 10 crimes at Fulton County. In January, he filed a motion to dismiss all charges against him on the basis of presidential immunity. In a brief the former president’s lawyer, Steven Sadow, wrote that “Presidential immunity from criminal prosecution for official acts has deep roots in the separation of powers and principles of federalism.” The Supreme Court has now adopted that position, strengthening his client’s hand. 

The Nine tell trial court judges — federal and state — that when assessing whether an action qualifies as an “official act,” motive is to be ignored in favor of an “objective analysis of ‘content, form and context.’” During oral arguments at the high court in April Trump’s attorney, John Sauer, appeared to concede to Justice Coney Barrett that the allegations against his client with respect to so-called “fake electors” were private in nature.

Mr. Sauer’s concession came when the justice asked about the allegation that Trump, as president, pursued a plan to “submit fraudulent slates of presidential electors to obstruct the  certification proceeding.” The lawyer also allowed that Trump’s effort to “spread knowingly false claims of election fraud to spearhead his challenges to the election results” would also qualify as private, as would filing “false allegations to support a challenge” in court.

Trump’s attorneys in Georgia, though, are not bound by those concessions, and they are likely to remind Judge McAfee that the Supreme Court urged lower courts to understand official acts capaciously. One of Trump’s attorneys, Will Scharf, took to CNN on Monday night to declare that the former president’s camarilla believes the “assembly of those alternate slates of electors was an official act of the presidency.”

The Supreme Court’s mandate that a former president cannot be “prosecuted for conduct within his exclusive constitutional authority” could also capsize the charges against Trump that center on interactions with two of his co-defendants, Chief of Staff Mark Meadows and an attorney at the Department of Justice, Jeffrey Clark. Chief Justice Roberts’s opinion in the January 6 case states plainly that Trump is “absolutely immune from prosecution for the alleged conduct involving his discussions with Justice Department officials.” Those two have raised their service to the president as a possible defense.

Ms. Willis, should she be atop the case when  it returns to trial, would likely find it easier to persuade Judge McAfee that Trump acted in a private capacity when he, say, called Georgia’s Secretary of State George Raffensperger and told him to “find 11,780 votes, which is one more than we have, because we won the state.” It is to be seen, though, if that is enough to sustain the racketeering charges that knit the case together. 

The district attorney’s fate, though, will be decided first — oral arguments are tentatively set for October 4.