What is going to happen in respect of the investigations into Hillary Clinton’s wrongdoing if, as so many expect, she is next month elected president? Donald Trump insists that if he is elected he’ll appoint a special prosecutor to investigate the former first lady. We’re against it, but that doesn’t mean the questions are going to go away. Nor would her own election likely end them. So how would they be resolved?

The most startling possibility that we’ve heard is that Mrs. Clinton could yet be impeached for high crimes or misdemeanors committed before she acceded to the presidency. At first, the idea will sound ridiculous, but only to those who have not read the lastest posting of Richard Epstein. The Laurence Tisch Professor of Law at New York University, he is one of America’s most distinguished legal scholars. And no fan of Donald Trump, as he makes clear in a blistering open letter to the GOP nominee this week.

What caught our eye in Mr. Epstein’s open letter – the FutureOfCapitalism.com linked to it on the Web site of the Hoover Institution – is his disclosure that he’s been consulting his colleagues on the scope of the Constitution’s impeachment clause. The clause is the part of Article II that says the President “shall be removed from Office on Impeachment for, and conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.”

Does, Professor Epstein asks, that provision “apply to actions that were committed by Clinton prior to” Mrs. Clinton’s anticipated election as President? Like, say, when she was Secretary of State? Mr. Epstein tells us that there’s not a lot, or even any, case law on the question. There have been, after all, but two presidential impeachments in our history. In his Hoover posting, he calls it “a serious interpretive question that we should hope never arises.”

Yet, the professor writes of Mrs. Clinton, “unless fresh revelations cease simply because she is elected President, this question could occupy public attention long after” Donald Trump’s own “juvenile antics have become old news.” (In his open letter to Mr. Trump Mr. Epstein reminds that Yale professor David Gerlernter, who will vote for the GOP nominee, sees impeachment as a “vital safeguard” against Mr. Trump’s own potential abuses of power.)

When one stops to think about it, in any event, it’s not so illogical that a president could be subject to impeachment for prior high crimes or misdemeanors. What, for example, if a president were discovered while in office to have murdered someone prior to being sworn in? Or to have once spied for an enemy? These are hypothetical questions, to be sure, but no less illuminating on the point. Were the GOP to hold the House and the House’s various probes to end in impeachment, would the Senate refuse to hold a trial?

The New York Sun has been in the camp that has preferred not to make a megillah out of Mrs. Clinton’s alleged wrong-doing. We have preferred to levy this campaign in respect of the issues — trade, taxes, monetary reform, immigration, the war, the Iranian deal, Israel, religious freedom, and basic constitutional principles. We are marking this point because we’ve long admired Professor Epstein as one of the keenest constitutional minds in America, and a long newspaper life has taught us that politics can take unexpected turns.