"Somebody fact checks on ads? You contract with someone to do that. Is that right?" Waters, a California Democrat, asked Zuckerberg. "Yes," he replied.
Later, during an exchange with Democratic U.S. Rep. Alexandria Ocasio-Cortez, Zuckerberg explained that his company will not remove political ads from candidates — even if false — because he believes voters deserve unfiltered access to the words of politicians. He said exceptions would be made for political ads that encouraged violence or seek to suppress voting.
Facebook on Thursday sought to set the record straight, noting that while it will not fact check political ads from candidates, it does evaluate the accuracy of political ads from political advocacy groups or political action committees.
"In a democracy, people should decide what is credible, not tech companies," the company wrote in a statement emailed to The Associated Press on Thursday. "That's why - like other internet platforms and broadcasters - we don't fact check ads from politicians."
Facebook's policy is similar to those at other big tech companies that have declined to remove false ads, reflecting a reluctance to police political content on their platforms.
CNN chief Jeff Zucker called Facebook's policy not to monitor political ads for truth-telling "ludicrous" Thursday. He noted that his network recently rejected two ads that President Donald Trump's campaign sought to air, saying they repeated allegations against former Vice President Joe Biden that had been proved false.
Facebook ran a similar ad.
Zuckerberg's comments on Facebook's hands-off policy also failed to satisfy Waters, who said Wednesday it would give "anyone Facebook labels a politician a platform to lie, mislead and misinform the American people, which will also allow Facebook to sell more ads. The impact of this will be a massive voter suppression effort."
Earlier this month, Democratic presidential candidate and U.S. Sen. Elizabeth Warren of Massachusetts created an intentionally false Facebook ad claiming that Zuckerberg had endorsed Trump for reelection. Warren did so to highlight her critique of Facebook's political-ad policies.
During his exchange with Ocasio-Cortez, Zuckerberg also made misleading comments about the company's reliance on third-party fact-checkers to evaluate false news stories posted to the site.
Ocasio-Cortez asked Zuckerberg why Facebook had made the conservative publication The Daily Caller one of its third-party fact-checkers.
In actuality, the fact-checking company is Check Your Fact, a subsidiary of The Daily Caller. The Daily Caller was founded by Fox News Channel host Tucker Carlson, who has been criticized for declaring white supremacy a "hoax."
"We actually don't appoint the independent fact-checkers," Zuckerberg said in a response. "They go through an independent organization ... that has a rigorous standard for who they allow to serve as a fact-checker."
Not so, said Baybars Orsek, who directs that organization, the International Fact-Checking Network at the St. Petersburg, Florida-based Poynter Institute.
"It is a misrepresentation of the program," he said, explaining that his network works to certify fact-checking organizations, including Check Your Fact.
Facebook requires its fact-checkers to be network certified but has the final say on which fact-checkers it works with.
"They make their decisions based on their priorities," he said. "We do not appoint fact-checkers to work with Facebook."
The AP is a participant in Facebook's initiative to fact-check and identify misinformation being shared widely online on Facebook's platform.