A Republican congressman’s grilling of Mark Zuckerberg over Facebook’s approach to anti-vaccination content exposed the high-wire balancing act the platform now faces as it seeks to balance a public commitment to free expression with efforts to clamp down on disinformation.

At first glance, the line of questioning Wednesday by GOP Rep. Bill Posey of Florida appeared odd and out of step with a hearing dominated by a discussion of Libra, the digital cryptocurrency the company hopes to establish.

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But taken in the context of Facebook’s desire to push back on fake news while allowing users to share their own views and opinions, it made more sense.

“I support vaccinations of children and adults, but I also support open and frank communication about the risks of vaccination,” Posey told Zuckerberg. “You testified that you believe in giving people a voice. Is Facebook able to assure us it will support users’ fair and open discussions and communications about the risks as well as the benefits of vaccinations?”

The U.S. medical community broadly agrees that the science behind vaccine safety is well established and that there is no link between early childhood vaccinations and autism.  In March, Facebook said it would no longer recommend anti-vaccination pages or groups to “tackle vaccine misinformation on Facebook by reducing its distribution and providing people with authoritative information on the topic.”

But in a speech at Georgetown University last week, Zuckerberg defended the rights of users to express their opinions openly and said he doesn’t think people “want to live in a world where you can only post things that tech companies decide are 100 percent true.”

Zuckerberg responds

Responding to Posey, Zuckerberg sought to have it both ways.

“We do care deeply about giving people a voice and freedom of expression,” Zuckerberg said. “At the same time, we hear consistently from our community that people want us to stop the spread of misinformation. So what we do is try to focus on misinformation that has the potential to lead to imminent or physical harm, and that can include especially misleading health advice.”

Posey responded by asking whether Zuckerberg is positive that vaccines don’t pose health risks.

“I don’t think it would be possible for anyone to be 100 percent confident but my understanding of the scientific consensus is that it’s important that people get their vaccines,” he responded.

Zuckerberg said anti-vaccination users on Facebook have the same rights to expression as others, and their views aren’t censored. However, he said, they aren’t publicized, either.

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“If someone wants to post anti-vaccination content or they want to join a group where people are discussing that, we don’t stop them from doing that,” said Zuckerberg. “But […] we don’t go out of our way to make sure our group recommendation systems show people or encourage people to join those groups. We discourage that.”

Posey concluded his line of questioning by telling Zuckerberg that many of the people harmed by Facebook’s policy are parents of disabled children, and that he doesn’t think the government or Facebook “should be so quick to turn our backs on them.”

“If you look at the statistics, I think you’re making a bad mistake,” he told Zuckerberg, without specifying which statistics he was talking about.

While maintaining a publicly pro-vaccine profile, Posey has spent years working quietly working alongside parents and others who believe in a link between vaccinations and autism, according to a report by the Orlando Sentinel.  In 2015, he said Congress should investigate claims by a former scientist at the Centers for Disease Control who claimed the agency withheld findings that linked autism to the measles vaccine. 

Zuckerberg’s pro-free expression stance has incurred scrutiny from Democrats who say he’s making excuses for the company’s new policy on political advertisements, which effectively allows politicians to lie because Facebook is not referring claims made in campaign ads to its third-party fact-checkers.

Following its decision to allow an ad by President Donald Trump’s reelection campaign that makes unproven allegations about former Vice President Joe Biden, Trump’s potential rival in the 2020 election, Sen. Elizabeth Warren, D-Mass., another Democratic candidate, accused the company of running a “disinformation-for-profit machine.”