By Ryan Tracy

WASHINGTON -- Facebook chief executive Mark Zuckerberg said Congress should consider forcing digital platforms to earn the legal immunity they enjoy hosting third-party content, a legal change that could affect a range of online businesses.

In written testimony submitted ahead of a House committee hearing Thursday, Mr. Zuckerberg suggested changes to Section 230, the law that says platforms such as Facebook generally aren't liable for what their users post.

"Instead of being granted immunity, platforms should be required to demonstrate that they have systems in place for identifying unlawful content and removing it," he said.

The comments were the most detailed yet from Mr. Zuckerberg on the issue. He had previously signaled openness to changing Section 230 in more general terms.

Both Democrats and Republicans are concerned that Section 230 gives large tech companies too much leeway to decide what information Americans see, though the parties have different concerns.

The law, an element of the 1996 Communications Decency Act, helped fuel the growth of social media by giving internet platforms immunity for comments that users, reviewers, consumers and others post on their sites.

Evan Greer, deputy director of the advocacy group Fight for the Future, said her group opposes scaling back 230 protections on grounds that doing so could devastate smaller platforms and internet startups that don't have the resources of tech giants.

"Of course Facebook wants to see changes to Section 230," Ms. Greer said. "Because they know it will simply serve to solidify their monopoly power and crush competition from smaller and more decentralized platforms."

Mr. Zuckerberg's testimony was released in advance of Thursday's hearing of the House Energy and Commerce Committee on "social media's role in promoting extremism and misinformation." Possible changes to Section 230 are expected to be a key focus of the hearing.

Many Republicans think social media platforms are removing too much content, while Democrats see them not removing enough and allowing harmful content to spread.

To date, those divisions have stood in the way of any consensus on how to change Section 230, and no bill to do so has gained significant traction on Capitol Hill. Facebook has been publicly supporting internet regulations for months, as it faces scrutiny over alleged antitrust violations and its content-moderation practices.

Thursday's hearing will give lawmakers a chance to question tech leaders on possible changes. Mr. Zuckerberg will testify by videoconference alongside Twitter CEO Jack Dorsey and Sundar Pichai, CEO of Alphabet Inc., which owns Google and YouTube.

Twitter and Google have indicated they are open to discussing legal changes with Congress, but they have been less specific than Facebook about what Section 230 changes they would support.

"Regulation has an important role to play in ensuring that we protect what is great about the open web," Mr. Pichai said in an advance copy of his written testimony. "We are, however, concerned that many recent proposals to change Section 230 -- including calls to repeal it altogether -- would not serve that objective well."

In his advance testimony, Mr. Dorsey said he agreed that "technology companies have work to do to earn trust from those who use our services."

His testimony didn't mention Section 230, but he has previously cautioned lawmakers that some proposed changes could end up favoring large companies with the budgets to navigate a more complex regulatory environment.

Mr. Zuckerberg said Section 230 protection could be made "conditional on companies' ability to meet best practices to combat the spread of this content," referring to unlawful content.

"Platforms should not be held liable if a particular piece of content evades its detection -- that would be impractical for platforms with billions of posts per day -- but they should be required to have adequate systems in place," he added. An "adequate system" could be defined by a third party and could be proportionate to a platform's size, he said.

In other issues likely to be aired at Thursday's hearing, Democrats are expected to ask about the Jan. 6 Capitol riot and Covid-19 misinformation. Republicans are likely to press the CEOs on their decision to suspend or remove former President Donald Trump's social media accounts after Jan. 6.

Write to Ryan Tracy at ryan.tracy@wsj.com

(END) Dow Jones Newswires

03-24-21 1445ET