The House of Representatives on Tuesday overwhelmingly passed a controversial sex trafficking bill that is now headed to the Senate, where it’s expected to pass by a wide margin. Few politicians would shy away from rallying around a cause like combating sex trafficking, but sex workers and civil liberties groups warn that the bill could have the effect of restricting online free speech and endangering sex workers.

The bill, titled the “Allow States and Victims to Fight Online Sex Trafficking Act,” or FOSTA, is aimed at curbing online sex trafficking by holding online platforms legally liable for any content found to “knowingly assist, facilitate, or support sex trafficking.” It gives victims and prosecutors the power to take legal action against an online company if its conduct violates federal sex trafficking laws, but in turn chips away at immunity that websites have had since the 1990s under the Communications Decency Act.

The final version of the House bill, which passed 388-25, included an amendment to Section 230 of the Communications Decency Act, which gives online platforms broad immunity from the actions of their users, with several narrow exceptions. The amendment, offered by Rep. Mimi Walters of California, borrowed language from the Senate version, the Stop Enabling Sex Traffickers Act, or SESTA. Under that amendment, websites that promote or facilitate prostitution can be prosecuted, making it easier for sex trafficking survivors to take websites to court and win. But opponents of the legislation point out that laws punishing websites for enabling sex trafficking already exist: Under the original language of Section 230, platforms that violate federal laws by hosting advertisements for sex trafficking are not immune from prosecution.

Michael Macleod-Ball, First Amendment adviser to the American Civil Liberties Union, said a primary concern is the fact that the bill provides a template for others who may want to restrict online speech.

“Nobody is arguing that sex trafficking isn’t a real issue or anything like that,” Macleod-Ball said. “But there are a whole host of really bad things in this world and I think with this bill — if it becomes law — is a step for the next advocacy group to come along and say, ‘Oh, we think this is the worst thing in the world, and we really need to do something about it, and we’re gonna put the onus on online platforms to make sure that this isn’t a problem online.’”

Sex workers are also actively campaigning against the bill. As a group, they are believed to be disproportionately impacted by violence and policing, but there is a dearth of comprehensive reporting due to the underground nature of the industry. According to a 2004 report, sex workers have a much greater risk of being murdered compared to the general population and any other job. Worldwide, sex workers have a 45 to 75 percent chance of experiencing violence at some point in their careers and too often, violence and rape go unreported due to the threat of getting arrested. They oppose the bill because if it becomes law, it would threaten their very livelihood and safety. They have been organizing under the hashtag #SurvivorsAgainstFOSTA, asking people to call their representatives in Congress.

“Just got off the phone with Congressional staff member. Told him about the murder of my friend Sequoia, who did not have access to online screening for clients. May Congress know her name when they vote # SurvivorsAgainstFOSTA,” writer and porn performer Lorelei Lee tweeted.

Sex work refers to a broad industry that includes prostitutes, escorts, strippers, nude cam models, dominatrixes, pornography actors, and phone sex operators, among other jobs. Trafficking, on the other hand, involves forcing someone into sex work through violence or coercion. Under FOSTA, that distinction is not very clear.

“H.R. 1865 creates the new offense of intentional promotion or facilitation of prostitution while using or operating a facility or means of interstate or foreign commerce, such as the internet,” Rep. Sheila Jackson Lee, D-Texas, explained on the House floor. “A general violation of this offense will be punishable by a sentence of upwards of 10 years.”

Because the language used to define trafficking resembles that used to describe sex work, sex workers fear they will be unfairly targeted under FOSTA, which will make it more difficult to find clients and make a living. Indeed, the Electronic Frontier Foundation noted that a computer would not be able to distinguish between a legitimate sex work post and one that supports sex trafficking with anything approaching 100 percent accuracy, so “platforms would have to calibrate their filters to over-censor.” And when web platforms “rely too heavily on automated filters,” the EFF added, “it often puts marginalized voices at a disadvantage.”