Presidents might not even be immune from criminal charges

Federal prosecutors are barred from charging a sitting president with a crime because the Justice Department has decided that presidents have temporary immunity while they are in office. The special counsel, Robert S. Mueller III, was following that direction when he said in May that presidents could not be charged.

That position is outlined in two Justice Department memos written during the Nixon and Clinton administrations, citing the burden that a barrage of investigations would put on the president. But Judge Marrero called it into question. He said the memos rely on “suppositions, practicalities and public policy” as well as dire pictures of hypothetical scenarios — and not on an actual case.

Either way, those memos — themselves interpretations of the Constitution — do not bind the hands of a local prosecutor such as Mr. Vance. Still, the question of whether a president can face state criminal charges also has never been tested, the judge noted.

The question could reach the United States Supreme Court

Mr. Trump’s lawyers quickly appealed Judge Marrero’s decision to the Second Circuit Court of Appeals in Manhattan. Depending on what happens there, the losing side ultimately could try to take the case up to the Supreme Court.

The Department of Justice said on Monday that it planned to weigh in on the case as well.

That does not mean the high court would agree to take the case. But if it does, it could set a sweeping new constitutional precedent about presidential immunity. Did the framers intend for impeachment by the House and conviction by the Senate to be the only vehicle for handling any wrongdoing by the president? Should prosecutors with possible political bias have the unfettered ability to disrupt a presidency? Is no American above the law?

Even if the district attorney wins, the president’s tax returns would not be made public

The president has fought multiple attempts to obtain copies of his tax returns, which he said during the 2016 campaign that he would make public but has since refused to disclose.

Mr. Trump’s lawyers have sued to block attempts by congressional Democrats to access his tax returns and financial records, and by New York lawmakers to release state tax returns to congressional committees. They also successfully challenged a California law requiring presidential primary candidates to release their tax returns.