I'm sorry I didn't see this until just now––I was away from the computer.
Here's what you wrote (this is mostly for my reference):
Suppose the cops had intelligence, which they found credible, that a flash mob would be organized via cell phone and face book in an identifiable Area A for the purpose of causing residents of Area A to meet at a stated time in an as yet unidentified Area B for the purpose of engaging in violence, theft, and destruction of property in Area B.
What if any steps do you believe the police should be permitted to take in response to this intelligence? What if residents of Area A have done just this on two prior occasions in the past year, with resultant injury to persons and property in other parts of town? How would you suggest the police go about doing whatever you would allow them to do?
I realize this question is a "should LE/the state be able to suspend cell phone coverage and somehow restrict facebook?"
First cell phone coverage.
This differs from the apparent scenario in San Francisco. There, as I understand it, you had government (local) owned cell phone towers. There the government decided to cut cell phone coverage to prevent people from meeting. I don't know the background of that scenario other than the one article posted, so I do not know if that scenario involved a flash-mob (of the dangerous kind) or some sort of peaceable protest. The combination of lack of facts in the SF scenario and the government-owned (or operated) cell phone towers distinguish it from this scenario. A further distinction is that LE in the SF scenario knew the location of the protest/event.
In your scenario (call it Scenario B), here are the important facts as I see them:
A flash-mob intending to cause "violence, theft, and destruction of property..."
The starting location of the mob is
defined and known as Area A.
The location to be mobbed is the
unknown Area B.
The same general mob has committed similar illegal acts on two prior occasions within the last year. Injuries and damage have resulted.
We know they are organizing using cell phones.
Should the police be able to cut cell phone service to Area A?
I do not know. I do not believe so––at least not without a court order. The cell phone towers are privately owned in this Scenario B, are they not? Since we do not know where Area B is, we cannot target that location to deny coverage, either. So we would have to cut service to an Area A that contains more than merely the criminal element.
Insofar as the mob is concerned, I do not believe there is a constitutional violation for cutting their cell phone service in this Scenario B as the towers are privately owned. There is, however, a possible claim to be raised by the cell tower company. I suppose one could argue a public necessity exemption to just compensation, but I don't think that's the point of this thread.
Now Facebook.
I do not see any issue with LE finding a way to get in on their Facebook group to get intel. It would be voluntary, so I do not believe it would be an illegal search if done without a warrant. Though I must admit I am no longer up to date on this stuff (I will be before February). But this aspect is pretty obvious and cut and dry.
Can LE/the state cut off the Internet? I think that's more difficult than the cell tower question. It is much easier to argue that 1st Amendment-protected speech (political and commercial, obviously) comes into play with the Internet. Let's assume that cutting off the Internet in Area A only is possible and easy, first of all. This might be a prior-restraint violation as the speech is being stopped due to its content. Granted, the speech can also be argued to be conspiracy. I think the greater problem here is the impact on the free speech rights of the non-mob residence of Area A.
However, why not simply arrest those who are planning the mob violence? If the intel is good enough to bring about these questions, and we know there is an Area B that will be mobbed, these people can be tried for conspiracy, can they not?
Aside from the above, why not have police monitor the residents? Increase police presence, generally. Get warrants and tap the lines (I don't know how to do this with cell phones, but I'm sure it's doable).
I have no problem with finding ways to stop these people. But we should err on the side of caution with regards to the Constitution. I think your Scenario B is so substantially different from the facts as I understand them in the SF scenario that the comparison is invalid. And please don't construe that as an insult––it's just how I see it. I do not know any more facts about the SF scenario than what I read in the one article. The article implied to me that the protest was a peaceful one, as well.
Regardless, I think it is heavy-handed and unnecessary to simply cut cell phone service. To me, that is parallel to simply ending commercial air travel if we get intel that some terrorist are going to use planes to attack ground targets again. If we got intel that there would be a flash-mob at the Orange Park Mall, should CCSO shut down the mall? Al Qaeda uses the Internet all the time to organize, but don't just shut it down. Terrorists in Iraq literally use cell phone calls to blow up bombs, but not even there do we cut cell phone service.
Going the route of cutting service is counter productive. Heck, if anything it plays right into the hands of people hoping for anarchy.
I apologize for how stream-of-consciousness this is. I haven't written a memo of law in far too long, and I wrote this too fast with no research. No one wants to hire a JD who isn't barred yet. Students cost less (saying you'll work for student wages hasn't worked, either, haha).
I think my point about prior restraint is garbage, by the way.