Reddit’s chief executive plans to warn Congress that an attempt to limit websites’ legal protections for content posted by users would harm online publishers — particularly smaller ones.

“Even small changes to the law will have outsized consequences for our business, our communities, and what little competition remains in our industry,” Steve Huffman, co-founder and CEO of the news and information-sharing site, says in prepared testimony.

Huffman is among the witnesses slated to testify at a hearing about potential changes to Section 230 of the Communications Decency Act, which provides that online platforms are immune from liability for users’ speech.

Section 230, considered one of the most important laws affecting the internet, broadly immunizes tech platforms from liability for users’ speech. The law protects review sites like Yelp from defamation lawsuits based on users’ critiques, and listings sites like Craigslist from negligence lawsuits based on products sold by users. (There are some exceptions to the immunity, including ones that apply when users post content that infringes copyright, violates a federal criminal law, or violates some sex trafficking statutes.)

While Section 230 allows platforms to moderate content, it doesn’t require them to do so.

Tuesday’s hearing, “Fostering a Healthier Internet to Protect Consumers,” convened by two subcommittees of the House Energy and Commerce Committee, will address how online platforms police users’ posts.

“The internet has become substantially more complex and sophisticated since the passage of CDA 230,” Energy and Commerce Chairman Rep. Frank Pallone (D-New Jersey) writes in a memo to the Subcommittees on Communications & Technology and Consumer Protection & Commerce.

“Problematic content, such as political disinformation, hate speech, extremist recruiting, cyberbullying, and election interference, among other things, is proliferating,” Pallone writes.

Pallone doesn’t outline any specific proposals for revisions, but other politicians on both sides of the aisle have recently pushed to revamp Section 230.

Sen. Josh Hawley (R-Missouri), for example, recently proposed stripping platforms of their immunity, unless they prove to the Federal Trade Commission that they don’t discriminate based on politics or viewpoint. And Democratic presidential hopeful Beto O’Rourke proposed that social media companies should lose immunity unless they create systems to remove “hateful activities” on their platforms.

Gretchen Peters, founder of the Alliance to Counter Crime Online — one of the witnesses slated to testify on Wednesday — will urge Congress to revise Section 230 to remove companies’ immunity for “hosting terror and serious crime content,” according to her prepared testimony.

“If it’s illegal in real life, it should be illegal to host it online,” she says in written remarks 

Huffman counters in his prepared testimony that any new obligations to monitor users’ content could harm small web companies.

“Even targeted limits to 230 will create a regulatory burden on the entire industry, benefiting the largest companies by placing a significant cost on smaller competitors,” his testimony states. “Many of the conversations on revising 230 are premised on companies having the ability to moderate content from the center, in an industrialized model often reliant on armies of tens of thousands of contractors. Medium, small, and startup-sized companies don’t have the resources for this.”

Google’s Katherine Oyama, head of intellectual property policy, is also among the witnesses expected to testify Wednesday.