>In other words, the purpose of the commerce power is to allow Congress to impose uniform economic regulation, to prevent states from putting up trade barriers, etc. The purpose is not to ease the "burden" of complying with the criminal statutes of 50 different states.

I don't think you can draw such a clean line between imposing uniform economic regulation and easing the burden of complying with divergent or conflicting criminal laws, or between criminal law and economic regulations. Most "economic regulations" are enforced with criminal penalties and most crimes would be markets if the activity weren't prohibited.

I don't think the important distinction is between criminal and commercial law (given that the latter can be read to encompass nearly anything) but rather a question of what commercial activity is inherently interstate and therefore a suitable area for the federal government to preempt the states and put down uniform rules. And the internet practically defines such a thing because anything on the internet is available everywhere all at once.

You don't want local regulations to apply to the internet. A company doing business on the internet doesn't choose (or necessarily even know) which jurisdictions visitors to its website reside in. The default state of a website is to be available world-wide. The most analogous historical activities are the interstate highway system, the postal service and long distance telecommunications, which have always been prime candidates for federal preemption, and even there you generally have a much better idea of which jurisdictions you're doing business with.

The existing CDA is extremely well suited to the internet because it still allows local criminal regulations to be enforced against local defendants, it just doesn't allow states to leverage the existence of local intermediaries into jurisdiction over the the entire internet. All it really prevents is for states to enforce regulations by proxy against citizens outside of their jurisdiction.

And prohibiting enforcement by proxy is good policy in any event because it leaves the application of criminal law in the hands of the justice system rather than corporate intermediaries. If AT&T or YouTube has to worry about local criminal liability for what users do on the internet then they're just going to block everything anyone makes a claim about regardless of the validity because they don't have the expertise or the incentive to mount a thorough investigation. This is already the problem we have with the DMCA, but now you're handing that power to every state's attorney general and every would-be complainant that makes a noise about filing a criminal complaint if the intermediary doesn't take the material down, and even worse because the DMCA at least provides a safe harbor if the material is removed. The proposed change to the CDA would leave the intermediaries having to preemptively guess what material might possibly violate any local criminal ordinance. They would have to moderate everything -- and then what about real time communications? Does it really make sense to subject Skype to criminal penalties if teenagers use it to sext each other?

Meanwhile the users have no remedy against frivolous take downs or refusals to carry speech because there is no judgment, just a prophylactic removal by a risk averse corporation which the user has no real recourse against.

>Again, I think it's stupid. We should just abolish the states and turn them into administrative districts. But to the extent that we don't entertain that idea, we have to accept the fact that the pain of complying with 50 different ideas of what criminal law should be exists by design.

I really don't think it does. The states are supposed to exercise local jurisdiction over local activity. The whole thing with Brandeis and laboratories of democracy. You let Alabama and California and Nevada all try different things and see what works. But you can't do that with inherently interstate activities because instead of 50 experiments you just end up having the most restrictive rules of any state be controlling, which is half the point of putting interstate commerce under federal jurisdiction. (The other half is discouraging protectionism as you point out.)