Facebook refuses to fact-check political ads, and it's infuriating employees and lawmakers. Here's why the issue has become Facebook's latest major controversy.

In late September, Nick Clegg, Facebook's vice president of global affairs and communications, laid out Facebook's policy on political ads: "Facebook exempts politicians from our third-party fact-checking program."

Facebook relies on third-party fact-checking for the majority of ads run on its social network. It adheres to an international standard for fact-checking: The International Fact Checking Network, run by Poynter.

That third-party fact-checker scrutinizes "public, newsworthy Facebook posts, including ads, with articles, photos, or videos." There is one exception to this fact-checking effort: political advertising.

Facebook lays out its reasoning in an official document. Under the question, "Why are politicians not eligible?," the explanation is as follows: "Our approach is grounded in Facebook's fundamental belief in free expression, respect for the democratic process, and the belief that, especially in mature democracies with a free press, political speech is the most scrutinized speech there is. Just as critically, by limiting political speech we would leave people less informed about what their elected officials are saying and leave politicians less accountable for their words."

This is at the heart of Facebook's latest controversy: The company refuses to fact-check political ads.

Facebook says this isn't about the money it makes from running political ads.

When a political ad runs on Facebook, whoever runs that ad has to pay Facebook. Given that, it stands to reason that Facebook's interest in keeping political ads is a question of profit.

Not so, says Facebook.

"We're not doing it because of the money," Facebook COO Sheryl Sandberg said in a recent interview with Bloomberg. "This is less than 1% of our revenue and the revenue is not worth the controversy."

Zuckerberg made a similar argument during Facebook's most recent investor earnings call.

"In a democracy, I don't think it's right for private companies to censor politicians or the news," he said. "And although I've considered whether we should not carry these ads in the past, and I'll continue to do so, on balance so far I've thought we should continue. Ads can be an important part of voice — especially for candidates and advocacy groups the media might not otherwise cover so they can get their message into debates."

He added that next year — amid a flurry of presidential campaigns — less than half of a percent of Facebook's revenue will come from political ads. The messaging is clear: This isn't about the money, it's about a principled stand.

So, what is it about? According to Zuckerberg, it's about free speech.

During his speech at Georgetown University in mid-October, Mark Zuckerberg laid out a full-throated defense of Facebook's reason for not fact-checking political ads.

Here's Zuckerberg's argument (emphasis is ours):

"We recently clarified our policies to ensure people can see primary source speech from political figures that shapes civic discourse. Political advertising is more transparent on Facebook than anywhere else — we keep all political and issue ads in an archive so everyone can scrutinize them, and no TV or print does that. We don't fact-check political ads. We don't do this to help politicians, but because we think people should be able to see for themselves what politicians are saying. And if content is newsworthy, we also won't take it down even if it would otherwise conflict with many of our standards.

I know many people disagree, but, in general, I don't think it's right for a private company to censor politicians or the news in a democracy. And we're not an outlier here. The other major internet platforms and the vast majority of media also run these same ads."

In short, Zuckerberg believes that banning political ads from Facebook — or fact-checking them — would be overstepping Facebook's role. His argument is rooted in American law and the so-called "marketplace of ideas."

The logic is simple: Freedom of all speech — facts and lies and everything in between — enables a transparent public discourse, and that public discourse, over time, leads to "the truth" as bad ideas are discarded and good ideas win out.

Critics — including Sen. Elizabeth Warren and Rep. Alexandria Ocasio-Cortez — argue that Facebook is doing a disservice to the public by not fact-checking political ads. Facebook's own employees wrote a letter to Zuckerberg challenging the decision.

Nearly as soon as Facebook began clarifying and defending its policy of not fact-checking political ads, criticism began.

The criticisms are many and varied.

Facebook's former head of global elections integrity ops, Yaël Eisenstat, just published a scathing op-ed against the decision in the Washington Post. "The real problem is that Facebook profits partly by amplifying lies and selling dangerous targeting tools that allow political operatives to engage in a new level of information warfare," Eisenstat wrote on Monday.

Additionally, a group of current Facebook employees collaborated on a letter they sent to Mark Zuckerberg internally.

"Free speech and paid speech are not the same thing," the letter reads, according to a copy of it published by The New York Times. "Misinformation affects us all. Our current policies on fact checking people in political office, or those running for office, are a threat to what FB stands for. We strongly object to this policy as it stands. It doesn't protect voices, but instead allows politicians to weaponize our platform by targeting people who believe that content posted by political figures is trustworthy."

Both Rep. Ocasio-Cortez and Sen. Warren backed the letter and the employees who wrote it.

"Facebook's own employees know just how dangerous their policy allowing politicians to lie in political ads will be for our democracy," Warren wrote. "Mark Zuckerberg should listen to them — and I applaud their brave efforts to hold their own company accountable."

That's just a small smattering of folks who have criticized the move.

No matter where you land on the controversy, one thing is for certain: It's a tremendously complicated issue.

Twitter recently made the decision to outright ban political ads.

"This isn't about free expression," Twitter CEO Jack Dorsey said on Twitter, where he announced the ad policy change. "This is about paying for reach. And paying to increase the reach of political speech has significant ramifications that today's democratic infrastructure may not be prepared to handle. It's worth stepping back in order to address."

Some politicians praised the move, including former Vice President Joe Biden and former Secretary of State Hillary Clinton — but President Trump's campaign manager, Brad Parscale, asserted that the move was, "yet another attempt to silence conservatives."

If Facebook were to ban political ads, it would run into another issue — one that Twitter is almost certain to face: deciding what is and isn't "political" speech.

Zuckerberg highlighted as much during his speech at Georgetown.

"Even if we wanted to ban political ads, it's not clear where we'd draw the line," he said. "There are many more ads about issues than there are directly about elections. Would we ban all ads about healthcare or immigration or women's empowerment? If we banned candidates' ads but not these, would that really make sense to give everyone else a voice in political debates except the candidates themselves?"

It's a reasonable point — if Facebook were to ban "political" ads, it would have to spend a lot of time defining what is and isn't political speech. And then it would come under fire for policing free speech.

"There are issues any way you cut this," Zuckerberg said, "and when it's not absolutely clear what to do, I believe we should err on the side of greater expression."