The United States Senate is moving toward passage of a bill that would—for the first time—water down a landmark 1996 law that shields website operators from lawsuits and state prosecution for user-generated content. And one of the authors of that 1996 law, Sen. Ron Wyden (D-Ore.), argued Tuesday that this would be a mistake.

The Stop Enabling Sex Trafficking Act now has 28 co-sponsors, and the breadth of that support was evident at a Tuesday hearing before the Senate Commerce Committee. The legislation would allow state attorneys general to prosecute websites that are used to promote sex trafficking—something that's currently barred by Section 230 of the 1996 Communications Decency Act. It would also allow private lawsuits against sites that host sex trafficking ads.

But Wyden argued at Tuesday's hearing that weakening Section 230 would be a mistake. In Wyden's view, Section 230 has been essential for establishing the United States as a global technology leader. It freed Internet startups from worrying about getting sued for hosting user-generated content, Wyden claimed. The section also allows startups to focus their resources on hiring developers and designers instead of lawyers.

"It has been the legal foundation for the growth of the Internet," Wyden said. "I believe it ought to be kept intact."

But other members of the Senate weren't convinced.

Sex trafficking is "on the increase," said Sen. Rob Portman (R-Ohio), a co-sponsor of the Stop Enabling Sex Traffickers Act at the Tuesday hearing. "And it's for one reason: online sale of girls, children, women. We've got to face that reality and deal with it."

Senators repeatedly blasted Backpage, a Craigslist competitor that has become a popular forum for both adult prostitution and the selling of underage girls for sex. A Senate report released late last year charged that Backpage repeatedly stripped terms like "lolita" and "little girl" out of ads—terms that strongly suggest an underage girl was being sold for sex—before posting the edited ads online. At Tuesday's hearing, some senators and witnesses expressed frustration that Section 230 has prevented state officials from prosecuting Backpage.

But critics of Portman's legislation counter that federal prosecutors already have the authority to prosecute sites like Backpage—the law only bars state and local prosecutions, they say. Indeed, the feds are rumored to be working with a grand jury in Arizona on an indictment against Backpage's founders. Defenders of Section 230 like Santa Clara University law professor Eric Goldman urged Congress to wait and see how that prosecution turned out before considering legislation to weaken Section 230.

They also warn that changing Section 230 could create perverse incentives for technology companies to be less aggressive about policing user-generated content. Section 230 is sometimes described as a "good Samaritan law," because it ensures that a website trying to filter out harmful material won't get blamed for harmful content the filters miss. Without the protection of Section 230, websites might decide that the safest course is to just not try to filter harmful content at all—since then the site can definitely say it wasn't aware of any specific harmful material.

While many senators expressed support for SESTA at Tuesday's hearing, it's not clear if the legislation has the critical mass needed to pass. Other senators stressed the value of finding a compromise that would satisfy both sides, a sign that they may not be prepared to vote for the bill in its current form.

Companion legislation has been introduced in the House and has 140 co-sponsors, but it hasn't yet been brought up for a vote.