The Trump administration is pushing to add legal protections in the North American Free Trade Agreement (NAFTA) that would limit the liability of internet giants such as Google and Facebook, marking the latest in a tug-of-war as policy makers balance policing the web with protecting free speech.

U.S. Trade Representative Robert Lighthizer included the proposal in an updated U.S. wishlist for NAFTA published during the fifth round of negotiations, which ended last Tuesday. It comes as U.S. senators are advancing a bill, backed by President Donald Trump’s daughter Ivanka Trump and Facebook Inc.’s Chief Operating Officer Sheryl Sandberg, that eliminates liability protections for websites that knowingly facilitate online sex trafficking. Some other tech companies and advocates have argued such legislation threatens to undermine their industry.

The U.S. is pressuring Canada and Mexico — the country’s top two export markets — to agree to limit “civil liability of online platforms for third party content,” according to the list of U.S. negotiating priorities published Nov. 17. A major U.S. technology group, the Internet Association, had urged it to push for such language.

Canada and Mexico have rejected the U.S. proposal, according to four officials familiar with negotiations, speaking on condition of anonymity. Canada doesn’t believe that type of provision belongs in a trade agreement, and also generally opposes reducing liability for internet companies, two of the officials said.

The administration’s move is in some ways a form of protectionism — the U.S. is in effect trying to enshrine protections for Silicon Valley in a trade agreement, essentially pushing policy beyond America’s borders.

Stifle Expression

In the U.S., a 1996 law largely protects websites from liability for what their users post. Many in the tech industry say that has allowed the internet to flourish.

Because web pages involved in the sex trade cite the provisions on third-party content in their defense, a bipartisan group of more than 40 senators, led by Republican Rob Portman, have sought this year to create exemptions to the law to punish those who knowingly abet trafficking or child pornography. There is also legislation in the House.

The lawmakers argue their proposal is narrow and wouldn’t harm the larger web, while tech advocates including the Internet Association — which includes Facebook, Alphabet Inc.’s Google, Twitter Inc. and others — argued in the past it could stifle free expression and curtail good-faith efforts to self-police.

The fight over liability protections has been one of several tech headaches in Washington. Facebook and Google have received stepped-up scrutiny over Russian election interference through web platforms and questions about the size and power of their businesses, even as they quietly hope to reap the benefits of the broadly pro-business atmosphere of the Republican administration and Congress.

Senator Ron Wyden, an Oregon Democrat, pledged this month to delay the bill because it would hurt startups and stifle innovation.

While several tech groups continue to worry, the Internet Association in October reversed course on the Senate bill, lauding its compromises.

‘Detailed Consultations’

The NAFTA proposal is for cases not related to intellectual property rights, and comes with a caveat — it would be “subject to NAFTA countries’ rights to adopt non-discriminatory measures for legitimate public policy objectives.” It’s unclear what measures countries could adopt to impose liability in certain cases.

Lighthizer defended the U.S. proposal, saying it’s based on exhaustive consultations with lawmakers.

“The U.S. digital trade proposal has been informed by detailed consultations with Congress and would not prejudice the right of the United States and our Nafta partners to address important public welfare issues,” Emily Davis, a spokeswoman for Lighthizer, said.

The NAFTA dispute over so-called “safe harbor” provisions for internet companies is one of the issues holding up an agreement on NAFTA ‘s digital trade chapter, as officials from the three countries push to strike whatever deal they can as other divisive U.S. proposals loom large. The fifth round of talks ended without finalizing any new agreements, and negotiations are scheduled through March.