WASHINGTON—Big internet firms are seeking to get liability protections they enjoy in the U.S. inserted into a renegotiated North American Free Trade Agreement, adding fuel to a fight over the legal shield that some lawmakers say has facilitated online sex trafficking.
The proposed change to Nafta would mean online platforms in all three countries would be protected from liability for activities of their users, such as harmful or illegal posts. It would generally mirror a law adopted by Congress in the 1990s to promote…