[DougWebb]

I guess I was thinking of Common Carrier status [0]:

The FCC classified Internet Service Providers as common carriers, effective June 12, 2015, for the purpose of enforcing net neutrality. Before that time, the Good Samaritan provision of the Communications Decency Act established immunity from liability for third party content on grounds of libel or slander, and the DMCA established that ISPs that comply with the DMCA would not be liable for the copyright violations of third parties on their network.

My understanding (which may be flawed) is that "ISP" covers things like discussion forums, public chatrooms, and private(ish) chat like Skype and Facebook Messenger, and that the liability immunity goes beyond libel and slander. But, ISPs that filter third-party content are not protected because they're exerting control over the content, and implicitly approve of anything that is not filtered.

[0] https://en.wikipedia.org/wiki/Common_carrier#Telecommunicati...