New blog post for the US CDA 230 debate: Six Constitutional Hurdles for Platform Speech Regulation. (You won't believe number three...) http://cyberlaw.stanford.edu/blog/2021/01/six-constitutional-hurdles-platform-speech-regulation-0

These are mostly NOT about what speech Congress can prohibit. They're about HOW Congress shapes real-world outcomes through clumsy dictates to platforms.
That clumsiness can be intentional and dangerous. Or it can be a natural outcome of our terribly snarled 1st Am case law.

The six:
1. Congress can’t ban constitutionally protected speech. (Somehow confusion on this is a major problem.)
2. Laws that restrict only illegal speech, but cause platforms to restrict legal speech, can violate the First Amendment. (I've written like ten things on this.)

3. Laws requiring platforms to remove speech and laws requiring them to reduce its “reach” both trigger First Amendment scrutiny.
(The degree of confusion, bad policy takes, and legal error caused by people not seeing this issue is kind of incomprehensible to me.)

4. Laws explicitly or implicitly requiring platforms to monitor and police their users raise multiple constitutional issues.
(Europeans are yawning over this one by now. Americans are about to get walloped by it. Oddly, EU focus here = speech and US focus here = privacy.)

5. Laws designed to regulate conduct are a bad fit for regulating online speech, but Congress has reason to use them anyway.
(This is a symptom of a deeper issue in our speech jurisprudence, and needs a class of experts with skills above my pay grade. #SympathyForTheRegulator)

6. Congress probably can’t avoid First Amendment restrictions by merely incentivizing, instead of requiring, platforms to take down lawful speech.
(This one needs serious attention. I only scratch the surface here.)

I'll do a follow-up blog post before too long using this checklist to assess the Eshoo/Malinowski PADA bill, which is the first real attempt to regulate "reach" of online speech I've seen.