Numerous tech companies have voiced their support for a bill currently working its way through Congress, the Stop Enabling Sex Trafficking Act (or SESTA), which is designed to make it easier for prosecutors to target websites that enable sex work. Wikimedia, the foundation behind Wikipedia, is concerned that the new bill will overreach, and make it difficult for sites built on user-generated content to continue to operate.

Senator Rob Portman of Ohio introduced SESTA in August, which aims to scale back part of Section 230 of the Communications Decency Act, which provides sites with immunity from liability the content that is generated by users. The bill has been criticized by groups such as the Electronic Frontier Foundation, which say that the provision helps protect freedom of expression on the internet.

In a post to Medium, Leighanna Mixter, Wikimedia’s Legal Fellow, says that there’s three principles in the provision that makes Wikipedia’s existence possible. First, CDA 230 helps encourage sites to host content and frees them up from concerns about being prosecuted over user-generated content. SESTA includes language that “expands liability for ‘knowing’ support of certain criminal activity,” that sites could be considered as participating in a crime, and could thus be charged. Mixter says that the wording around “knowing” is vague, and that without clear guidelines, reporting the crime could create a liability for the site.

Secondly, SESTA allows for states to hold sites liable as well, and that the internet needs a single, national standards to work with, rather than 50 separate standards. This would essentially create a huge burden for small sites and companies: they would need to continually monitor not only federal law, but a myriad of state laws, to ensure that they’re complying with them.

Finally, the foundation says that in many cases, “plaintiffs target online speech, they often go after the website, not the speaker.” It’s far easier to target the platform on which people are breaking the law, rather than tracking down the individuals. Section 230 helps protect sites from this in part, but SESTA could expand the liability that sites will face. “Even if these lawsuits are meritless,” Mixter says, “getting them dismissed demands significant time and resources.” Moreover, CDA 230 isn’t a pass for sites that knowingly facilitate illegal activity: those sites can be prosecuted under the provision.

The concern is that without the protection from CDA 230, smaller sites and companies like Wikipedia could be buried under the threat of prosecution, and could to take measures to protect themselves. Those increased threats could result in higher costs for those companies to operate, by making sure that they’re complying with the law, or by going to court more often. Mixter writes that the impact could be chilling for the future of the web: start ups or other innovative sites might simply never launch over concerns that they might be sued or prosecuted.