By Dr. Brian Dellinger

The 1990s and early 2000s saw the rise of a new form of online-only marketplace. Companies like Amazon, eBay, and Craigslist became household words by providing familiar services from the convenience of a computer monitor. In 2004, Backpage.com joined the online advertising market; as of 2011, it trailed only Craigslist in connecting sellers with interested buyers.

By then, Backpage had drawn controversy its peers largely escaped, primarily due to its sex-oriented “adult” section. Critics charged that the site deliberately overlooked user-posted ads that violated state laws, including ads for underage prostitution. A raft of lawsuits and criminal charges followed; to date, none of these legal challenges have succeeded.

Backpage’s defenses rest heavily on Section 230 of the Communications Decency Act, which reads in part, “No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider.” In other words, a webpage is not considered to be the author of advertisements it merely hosts; if those ads are illegal under state law, charges fall upon the submitters and not the site.

The Allow States and Victims to Fight Online Sex Trafficking Act, abbreviated FOSTA, aims to remove that defense. FOSTA modifies Section 230 to make a webhost liable for acting “with the intent to promote or facilitate the prostitution of another person.” In other words, Backpage need not itself author illegal advertisements; it suffices that Backpage deliberately “facilitate[s]” them. As of this writing, FOSTA has cleared Congress with overwhelming bipartisan support and has drawn high-profile praise from organizations like the Family Research Council, the Ethics & Religious Liberty Commission, and the National Center for Missing and Exploited Children. Major tech companies, including Oracle, IBM, and Hewlett Packard, have also backed the bill.

The goals of FOSTA supporters are noble, and Backpage is decidedly not. For all the bill’s support, however, it has garnered an equally impressive array of opponents, including tech giant Google, the online advocacy group Electronic Freedom Foundation, and the U.S. Department of Justice. Opposition crosses traditional party boundaries, with writers at both Slate and Reason arguing against the bill’s passage.

To understand this resistance, one must appreciate the original function of Section 230 of the CDA. FOSTA supporters have dismissively referred to this section as a “loophole” in prosecution of webhosts. It is not. The protections offered by Section 230 are deliberate and key to the shape of the modern internet. FOSTA’s changes threaten an enormous portion of ordinary web traffic and may worsen the problem they are intended to solve.

Much of modern Web browsing passes through a relative handful of hosting sites. Some, such as video provider YouTube, host user-generated media directly. Others, like Reddit or some parts of Facebook or Twitter, act as content aggregators, with users posting links to other websites. In either case, hosts risk users posting material that might be illegal in some jurisdictions. While such companies can attempt to filter data, monitoring all posts is flatly impossible. Reddit’s official reports suggest an average of half a million posts per day; by some estimates, 300 hours of new footage are uploaded to YouTube every minute. Web companies rely on Section 230 to guarantee that they are not liable for simply reposting someone else’s illegal media.

FOSTA threatens those protections. Under the new law, a host who was only partially successful in blocking sexual content might be accused of deliberately turning a blind eye to the rest. Backpage itself, which claims to report four hundred ads per month and to turn away countless more, is evidence for this possibility. The burden of even successfully defending against repeat charges could be fatal to a hosting company, and would be particularly devastating for tech startups.

None of the remaining options are attractive. Some sites might end licit services in order to avoid charges. (Some are already doing so; within days of the Senate’s approval, Craigslist discontinued its personal ad service.) FOSTA opponents thus argue the law would have a broad chilling effect on speech, as webhosts apply over-broad content bans to minimize their risk.

Paradoxically, other hosts might respond by abandoning filters altogether. FOSTA makes sites liable only if they demonstrate intent to facilitate prostitution or trafficking. If a host makes no attempt to monitor posted content, opponents argue, it displays no intent either for or against that content; a filter, on the other hand, invites the question of why any particular post was allowed to stand. In other words, FOSTA’s result might be a world in which Backpage and similar sites provide even less attempt to prevent illegal posts.

Perhaps most crucially, FOSTA declares that its changes “shall apply regardless of whether the conduct alleged occurred … before, on, or after [its] date of enactment.” Thus, Backpage could be charged tomorrow for hosting ads years ago, even if, at the time, hosting them was protected under Section 230. As the Department of Justice notes in its objection, that makes FOSTA an ex post facto law, a retroactive punishment that is strictly unconstitutional.

Despite worthy intentions, FOSTA stands to cause harm without accomplishing its intended good. President Trump should veto it; barring that, tech companies should challenge the law at the soonest opportunity.

Dr. Brian Dellinger is an assistant professor of computer science at Grove City College. His research interests are artificial intelligence and models of consciousness.