Dorsey, who will appear before the Senate Commerce Committee virtually, will call Section 230 of the Communications Decency Act “the internet’s most important law for free speech and safety,” and argue that repealing the law will lead to more policing of content, not less.

“We should also be mindful that undermining Section 230 will result in far more removal of online speech and impose severe limitations on our collective ability to address harmful content and protect people online,” Dorsey plans to say, according to his prepared remarks.

Zuckerberg will make a similar argument. “Platforms would likely censor more content to avoid legal risk and would be less likely to invest in technologies that enable people to express themselves in new ways,” a copy of his testimony reads.

The Facebook CEO appears open to changing the law, however. “I believe Congress should update the law to make sure it’s working as intended,” he plans to say.

The two executives will appear before the Senate panel at 10 a.m. in Washington alongside Sundar Pichai, CEO of Google parent Alphabet Inc.

Dorsey will also argue that repealing Section 230, which grants online platforms some legal immunity from the content its users post, will hurt startups that won’t have the resources to moderate content at scale the way big tech companies can. “Eroding the foundation of Section 230 could collapse how we communicate on the internet, leaving only a small number of giant and well-funded technology companies,” he says in the prepared testimony.

He’ll also call on tech companies like Twitter to offer users a choice between different algorithms that will determine what they see in their feed.