(Jacquelyn Martin/Associated Press)

This morning Sari Horwitz has what may be the most comprehensive account yet of what happened behind the scenes as FBI Director James Comey decided to essentially hand the 2016 presidential election to Donald Trump. It’s an extraordinary story, one that provides an important lesson that goes beyond this one election: Political events with sweeping consequences are determined by individual human beings and the decisions they make. That may not sound surprising, but it’s a profound truth that we often forget when we look for explanations in broad conditions and trends (which are still important) or theories about dark and complicated conspiracies that don’t exist.

Let’s start with this summary of what happened when the FBI informed the Justice Department that Comey wanted to go public with the news that the bureau was looking into some emails found on a laptop belonging to Huma Abedin, Clinton’s close aide, which would end up happening nine days before Election Day:

The official in Deputy Attorney General Sally Q. Yates’s office who received the FBI call immediately understood the explosive potential of Comey’s message, coming so close to the presidential election. Federal attorneys scrambled into offices on the fourth and fifth floors of Justice Department headquarters, where they huddled to figure out how to stop what they viewed as a ticking time bomb.

“It was DEFCON 1,” said an official familiar with the deliberations. “We were in­cred­ibly concerned this could have an impact on the election.”

Aides at Justice and the FBI — located in offices directly across the street from each other on Pennsylvania Avenue — began exchanging increasingly tense and heated phone calls, nearly a half-dozen throughout the afternoon and evening of Oct. 27 and into the next morning.

Justice officials laid out a number of arguments against releasing the letter. It violated two long-standing policies. Never publicly discuss an ongoing investigation. And never take an action affecting a candidate for office close to Election Day. Besides, they said, the FBI did not know yet what was in the emails or if they had anything to do with the Clinton case.

Remarkably, the country’s two top law enforcement officials never spoke. As Comey’s boss, Attorney General Loretta E. Lynch could have given the FBI director an order to not send the letter. But Lynch and her advisers feared that Comey would not listen. He seemed to feel strongly about updating Congress on his sworn testimony about the Clinton investigation. Instead, they tried to relay their concerns through the Justice official whom the FBI had called.

Their efforts failed. Within 24 hours of the first FBI call, Comey’s letter was out.

One of the points that comes through in Horwitz’s account is that both Comey and Lynch were consumed with fear that they’d be criticized by the Republican outrage machine. Comey worried that if he didn’t immediately go public with the fact that the FBI was looking at these emails, then Republicans would say he was covering up an investigation in order to help Clinton. And Lynch worried that if she ordered Comey to adhere to department policy and not go public, then Republicans would say she was covering up an investigation in order to help Clinton.

So both of them failed to do their jobs, Comey with an act of commission and Lynch with an act of omission. You can sympathize with the pressure they were under and say that hindsight is always 20/20, but the fact is that they failed, and it was because they didn’t have the courage to do the right thing. The next time you shake your head at the sight of Republicans yelling into cameras or talk radio microphones about how terribly angry they are at whatever they’re supposed to be angry at today, remember how politically useful all that noise can be.

Newly unsealed court documents revealed that the FBI told a federal judge that it needed to search a computer belonging to former congressman Anthony Weiner to continue an investigation of Hillary Clinton's use of a private email server. (Peter Stevenson,Victoria Walker/The Washington Post)

Even though Lynch deserves whatever criticism she’ll get, there’s no question that Comey’s misdeed was far worse. Here’s the decision he was faced with: If I go public with this matter, I’ll be violating explicit, long-standing departmental policy and probably skew the results of a presidential election. On the other hand, if I wait for the investigation to actually be completed … Republicans might say mean things about me. That’s the generous interpretation of his thinking; the less generous version would be that he was going to do everything in his power to make sure Trump won, which he certainly did in the end. And keep in mind that he had no idea what was in the emails on that laptop, because they hadn’t been examined yet. And that there was almost no reason to think there was anything problematic in them, which is exactly what the FBI found when it did examine them.

As we think about this issue and about the election more generally, we shouldn’t fall into the trap of thinking that blame or responsibility is zero-sum. People have been saying things like, “Russia/Comey didn’t force Hillary Clinton not to spend more money in Wisconsin!” which is true but irrelevant. Clinton certainly made mistakes during the campaign, as every candidate does. But in a race that was decided by 77,000 votes spread across Pennsylvania, Wisconsin and Michigan, there are many factors that can be said to have swung the election. Saying that things would have been different if one particular event hadn’t happened isn’t saying that nothing else mattered.

Why can we say that Comey’s decision to go public made the difference? It came at the tail end of an endless media campaign to convince the public that there was literally no issue in the world more important than whether Clinton used the wrong email account — not the economy, not terrorism, not health care, not climate change, nothing. One analysis showed that network newscasts devoted three times as much attention to the email story as to all policy issues combined. By the time the campaign reached its end, the one word Americans thought of when they heard the name Hillary Clinton was “email” (just look at these shocking word clouds from Gallup if you doubt).

Most of them couldn’t tell you what the email story was actually about, but they knew it had something to do with some kind of corruption or other, as Trump kept saying. And any story that had the word “email” in it — like the Russian hacking of John Podesta’s emails, which had absolutely nothing to do with what email Clinton used at the State Department — got mashed in the public’s mind into one big amalgam.

I’m not going to relitigate the email question here. But that was the context in which Comey and Lynch made their decisions. They knew full well that when Comey violated departmental policy to go public with this news, it would result in an explosion of “EMAAAAAIIILLLS!” coverage across every major news outlet in the United States, which it did. And copious evidence suggests that the race turned right then, as Comey’s message reinforced exactly the argument Trump was making about Clinton, late deciders swung toward him, and wavering Republicans came home to their party’s nominee.

And it happened because one person was determined to inject himself into the race, and the one other person who could have and should have stopped him didn’t have the guts to do it.