The second presidential debate — bloody, muddy and raucous — was just enough to save Donald Trump’s campaign from extinction, but not enough to restore his chances of winning, barring an act of God (a medical calamity) or of Putin (a cosmically incriminating WikiLeak).

That Trump crashed because of a sex-talk tape is odd. It should have been a surprise to no one. His views on women have been on open display for years. And he’d offered a dazzling array of other reasons for disqualification: habitual mendacity, pathological narcissism, profound ignorance and an astonishing dearth of basic human empathy.

To which list Trump added in the second debate, and it had nothing to do with sex. It was his threat, if elected, to put Hillary Clinton in jail.

After appointing a special prosecutor, of course. The niceties must be observed. First, a fair trial, then a proper hanging. The day after the debate at a rally in Pennsylvania, Trump responded to chants of “lock her up,” with “Lock her up is right.” Two days later, he told a rally in Lakeland, Florida, “She has to go to jail.”

Such incendiary talk is an affront to elementary democratic decency and a breach of the boundaries of American political discourse. In democracies, the electoral process is a subtle and elaborate substitute for combat, the age-old way of settling struggles for power. But that sublimation only works if there is mutual agreement to accept both the legitimacy of the result (which Trump keeps undermining with charges that the very process is “rigged”) and the boundaries of the contest.

The prize for the winner is temporary accession to limited political power, not the satisfaction of vendettas. Vladimir Putin, Hugo Chavez and a cavalcade of two-bit caudillos lock up their opponents. American leaders don’t.

One doesn’t even talk like this. It takes decades, centuries, to develop ingrained norms of political restraint and self-control. But they can be undone in short order by a demagogue feeding a vengeful populism.

This is not to say that the investigation into the Clinton emails was not itself compromised by politics. FBI director James Comey’s recommendation not to pursue charges was both troubling and puzzling. And Barack Obama very improperly tilted the scales by interjecting, while the investigation was still underway, that Clinton’s emails had not endangered national security.

But the answer is not to start a new process whose outcome is preordained. Conservatives have relentlessly, and correctly, criticized this administration for abusing its power and suborning the civil administration (e.g., the IRS). Is the Republican response to do the same?

Wasn’t presidential overreach one of the major charges against Obama by the anti-establishment GOP candidates? Wasn’t the animating spirit of the entire tea party movement the restoration of constitutional limits and restraints?

In America, we don’t persecute political opponents. Which is why we retroactively honor Gerald Ford for his pardon of Richard Nixon, for which, at the time, Ford was widely reviled. It ultimately cost him the presidency. Nixon might well have been convicted. But Ford understood that jailing a president for actions carried out in the context of his official duties would threaten the very civil nature of democratic governance.

What makes Trump’s promise to lock her up all the more alarming is that it’s not an isolated incident. This is not the first time he’s insinuated using the powers of the presidency against political enemies. He has threatened Amazon’s Jeff Bezos, owner of The Washington Post, for using the newspaper “as a tool for political power against me and other people. … We can’t let him get away with it.”

With exercising free political speech?

Trump has gone after others with equal subtlety. “I hear,” he tweeted, “the Rickets [sic] family, who own the Chicago Cubs, are secretly spending $‘s against me. They better be careful, they have a lot to hide!”

He also promises to “open up” libel laws to permit easier prosecution of those who attack him unfairly. Has he ever conceded any attack on him to be fair?

This election is not just about placing the nuclear codes in Trump’s hands. It’s also about handing him the instruments of civilian coercion, such as the IRS, the FBI, the FCC, the SEC. Think of what he could do to enforce the “fairness” he demands. Imagine giving over the vast power of the modern state to a man who says in advance that he will punish his critics and jail his opponent.

© 2016, The Washington Post Writers Group