No origin story of the internet would be complete without mentioning one of its legal pillars: Section 230 of the Communications Decency Act, a 21-year-old law that shields tech companies from liability for content posted by users. Silicon Valley has long argued that any change to the law would hamper free speech and destroy the internet as we know it. Now, outrage over sex trafficking, mixed with growing unease about Silicon Valley’s economic and political clout, may be pushing tech companies to loosen their grip on the shield.

The change emerged during a packed Senate hearing on Tuesday to debate The Stop Enabling Sex Trafficking Act (SESTA), which would amend Section 230 to create liability for internet companies that knowingly facilitate trafficking on their platforms.

Senator Rob Portman, an Ohio Republican who is among the bill’s co-sponsors, had asked Google and Facebook to testify; neither appeared. Instead, their perspective arrived by proxy, through the Internet Association, a trade group that counts Google, Facebook, and dozens of other tech companies as members. The group opposes the bill, but supports criminal prosecution of Backpage.com, which hosts personal ads that many law-enforcement officials believe are thinly veiled invitations for sex with underage girls, who are often the victims of trafficking.

During her testimony, Abigail Slater, the Internet Association’s general counsel, said for the first time that its members would also be open to altering the bedrock legislation. “We also support targeted amendments to the Communications Decency Act that would allow victims of sex trafficking crimes to seek justice against perpetrators,” Slater said, referring to both traffickers and websites that facilitate trafficking.

The testimony represents a sudden shift for the trade group and its members, who until now have opposed any changes in the law. Last month, survivors, their families, and advocacy groups protested “tech industry obstruction” against the bill. Mary Mazzio, a filmmaker behind “I Am Jane Doe,” a documentary about sex trafficking, and a vocal proponent of the bill, was so taken aback by Slater’s remarks that she wasn’t sure that she heard Slater correctly. “That was such a welcome surprise. It’s a huge deal and if that’s true, that would be amazing” says Mazzio. Previously, Mazzio says, Google, Facebook, and other Internet Association members had “largely refused to engage in any discussion at all” about changing the law.

The dispute is not about Facebook and Google’s efforts to stop sex trafficking on their sites. Both companies have helped develop technology to find and purge illegal activity on their own sites. Rather, the bill’s backers are at odds with the big tech companies for refusing to consider changes in the Communications Decency Act that would make it easier to prosecute operators such as Backpage. Last December, a California judge dismissed criminal charges against Backpage, its CEO and two of its former owners, agreeing that they were shielded by the law. That case had been brought by California’s then-Attorney General Kamala Harris, who is now a US senator.

Now, the industry’s steadfast refusal to consider changes in the law may be eroding. The potential shift comes amid other pressures on big tech companies, including a demand that executives testify about Russian influence on the 2016 election. Danielle Citron, a law professor at the University of Maryland who serves on Twitter’s Trust and Safety Council and worked with Harris on her Backpage efforts, says tech companies are facing “an amazing convergence of interest” in their inner workings, from bipartisan support for SESTA to a European Commission mandate that they better police hate speech on their platforms.

During Tuesday’s hearing, senators returned repeatedly to testimony from Yvonne Ambrose, who fought back tears to describe the brutal murder and rape of her 16-year-old daughter after an advertisement offering sex with the child was posted on Backpage. “Section 230 is standing in the way of justice for my child and other Jane Does out there like her,” Ambrose told the Senate committee. “I’m sure when this act was put into place in 1996 the internet was in its infancy and it was not intended to allow companies to legally sell children on the internet. But somehow a dollar has become more important than a human life. If you’re going to fix this problem, fix it.”

Some industry critics are skeptical that tech companies are changing their view. John Simpson, director of Consumer Watchdog’s privacy efforts, says it’s “somewhat disingenuous” for the Internet Association to support tailored amendments to the Senate bill, which he says is already much narrower than a similar bill in the House. Simpson says he suspects that tech companies want to draft something “that completely continues the status quo” around liability. Google and Facebook declined to comment.

Citron has doubts about the language of the bill, but no reservations about the need to update the Communications Decency Act. The idea that altering the statute would cause the internet to crumble is silly, she says, pointing out that the law adapts with new technologies. She compares the internet today to autos 100 years ago. “We came to see over time that cars were incredibly dangerous and that industry could bear the cost,” she says. That time has come for Silicon Valley. “It’s 20 years later. These companies are so rich.”