The government has floated the idea of shutting down social networking sites during major riots, so that trouble makers will not be able to use them to coordinate their activities. Needless to say this idea is stupid, knee jerk authoritarianism of the worst kind, as Obo explains here.
When looking at history it soon becomes apparent that riots occasionally occurred before Twitter was even invented- hard to believe I know but when I looked it up on Wikipedia it turned out there have been a handful of high profile riots throughout British & indeed World history. Who knew?
The only difference between people inciting violence by word of mouth or by Twitter is that with Twitter anyone dumb enough to advocate violence (Hello Jody McIntyre) leaves a trail of evidence. Shutting down Twitter & Facebook would make it harder to convict rioters later on.
There is also the small matter of it being a punishment for the innocent as well as the guilty- some people have used social media to instigate violence but many more have used social networks to find out where trouble is happening and avoid it.
All in all the proposal is gimmicky, counter productive and unworkable.Witless authoritarianism did not die with New Labour.