Many technology companies consider Section 230 of the Communications Decency Act to be the a foundation of the Internet economy. The 1996 law gives website owners broad immunity for content submitted by users. Advocates say that allows websites to host a wide variety of user-generated content without worrying about getting sued.

Now, Congress is considering the first significant change to the law in its 21-year history. Critics say certain websites have hidden behind the law while publishing ads for the sexual exploitation of children. Activists are pushing for legislation that would carve out a sex trafficking exception to Section 230, allowing state prosecutions and private lawsuits against websites that host ads for sex with children.

“We’ve crafted a law that protects a sector of business with complete immunity against civil actions by victims even where there’s evidence that that company has knowingly facilitated the trafficking of that child,” says Samantha Vardaman of the advocacy organization Shared Hope.