If federal authorities have their way, Facebook, Twitter and other social media sites will be forced to report users' activities under a new provision of the 2016 Intelligence Authorization Act.

The legislation was debated secretly in the Senate Intelligence Committee in a closed door session last week and sent to the Senate floor late last night.

According to the provision, any online service provider that "obtains actual knowledge of any terrorist activity ... shall provide to the appropriate authorities the facts or circumstances of the alleged terrorist activity." The companies would have to report tweets, videos, posts or other content exchanged online by users.

The provision does not define "terrorist activity," one of the problems the NSA exploited in provisions of the Patriot Act to collect phone data on all Americans; nor does it indicate what happens when companies turn over the information to the government, and what liabilities or penalties the companies will face.

Privacy advocates find the secretive legislation deeply troubling.

Technology companies would be forced to preemptively report what employees deemed "terrorist activity" without a request or warrant from Federal authorities, or even a clear definition on what qualifies as "terrorist activity," Emma Llanso, a director at the Center For Democracy and Technology told Washington Examiner.

"It would require every component of the online communications eco-system, your email provider, social media networks, internet service providers, to make reports directly to the government about a totally undefined category of activity and communication," said Llanso. "When you have that kind of obligation, there's a massive potential for over-broad compliance efforts by the intermediaries because they don't know, they won't know, exactly what it is they're being required to do by law."

"In this American democracy, we don't want our social media providers to be acting as essentially secret police," said Nate Cardozo, a Staff Attorney at the Electronic Frontier Foundation told Vocativ. "There is a First Amendment right to talk about ... controversial political, religious, social events of our time [and they are] absolutely protected speech. And requiring social media providers to rat out their customers for engaging in their First Amendment right to debate important topics is not something that is constitutional."

The legislation's proponents argue that the bill is in response to security experts' warnings on the Islamic State, who promote their terrorist activities heavily on social media sites like Twitter and Youtube. Since the Islamic State uses social media to recruit new members and for propaganda, their terrorist activity is completely out in the open on sites that the public, or Federal authorities, can search and find.

Speaking on condition of anonymity because the proposal is not public, a Senate source told Vocativ the legislation would not "force companies to do anything they're not already doing."

The social media giants currently take down objectionable material when they find it on their sites, but there is no formal reporting process to federal authorities currently in place. Twitter deactivates terrorists' accounts.

Lawmakers argue this is not enough.

"It is really the beginning of saying: 'Hey Mr. and Mrs. American technology, you have a responsibility too,'" said Sen. Dianne Feinstein, D-Calif., at Wednesday's Senate Intelligence Committee hearing. "We do that for child pornography — don't you think we should do it for possible terrorist acts?"

"Ultimately this is a higher-tech version of 'See something, Say something,'" said Michael Leiter, former director of the National Counterterrorism Center, to the Washington Post. "In that sense, I believe that there is value."

FBI Director James Comey declined to endorse the proposal Wednesday, calling it an "interesting idea" but saying that technology companies are already "pretty good about telling us what they see."

Comey added that he'd "want to hear out the other side. This is something I haven't read enough to give you an intelligent answer."

"It's one piece in the bigger puzzle to compel companies to police speech online," said Llanso. "The choice that communications providers will be making is, do they think someone's communication is wholly protected political speech, or is it just commentary on current events, or is it something that should be reported to the government? ... We're clearly very, very concerned about that."