Democrats and anyone else who sees a Donald Trump presidency as the quintessential “Nightmare on Elm Street” are booing FBI Director James Comey’s “October Surprise.” In a letter to the GOP-controlled Congress, Mr. Comey announced that the “investigation” into Hillary Clinton’s highly questionable use of a private email server while she was secretary of state has been reopened.

This is the same James Comey who months ago chastised Hillary for being “extremely careless” with classified information, but said no criminal charges were warranted. He has been pilloried by Republican nominee Donald Trump and the rabid right ever since. His “October Surprise” this week made him a darling of The Donald and those who would vote for Charles Manson over Hillary.

The timing of Mr. Comey’s letter is as suspect as it gets. When he sent it, he had no clue what might be found in the emails and no warrant to seize them. He injected himself into an already hyper-polarized presidential election without any supporting evidence. It may turn out that the emails incriminate Hillary, but Americans are innocent until proven guilty. For all Mr. Comey knows, the emails contain recipes and family photos.

His intrusion into the election is not only unprecedented, but dead wrong. Even President George W. Bush’s top ethics lawyer objected, saying that Mr. Comey’s letter is a violation of the Hatch Act, which bars use of an official position to influence an election.

True or not, the damage is done. Will it be enough to swing the election in Donald Trump’s favor? I doubt it, and the most recent polls do, too. Whatever the fallout, outraged Hillary supporters have no one to blame more than their candidate. Hillary created the email scandal, and could have dispensed with it multiple months ago. Instead, she lied about it and allowed it to grow into a cancer on her campaign.

Hillary will likely still win, but the email scandal will haunt her presidency — and the nation — for many Halloweens to come.