@IceCream that was my mistake.
Is it correct to believe that both individuals did show up to their respective "protests?"
There was a previous question "At what point should law enforcement officers engage in stopping a violent behavior?"
I don't know what are the tests for "being capable." However, if someone could provide the ruling we can determine what it is under British law.
However this is what I have found "competence capable of distinguishing right from wrong."
With the "Criminal Attempts Act 1981" the law isn't on their side. This cause should be a clear indication that you should pay to get a lawyer who would represent you.
There is a distinguish that you made. You "that none of my friends are gonna be doing any rioting." Unless shown otherwise, it seems that they would have followed through on their crime.
One individual actually showed up to the event, where he was promptly arrests. So, he was obviously capable. The second individual seems to have been caught by the fact that his actions was after the riots had started. He two was capable to distinguish right from wrong, as show by him take down his page. It would have been better for him to have issued an apology, or indicated it was a joke.
There is no disagreement that the sentences are harsh. However, they could have been harsher.
Reading an article, I just remembered something. The legal system doesn't reward incompetence.
http://www.guardian.co.uk/uk/2011/aug/17...-justified
To answer your question. Yes, that individual should be charged. Whether it is banning you from Facebook, fining them, or sending you to prison. Let me explain the reason.
With the riots on going in London, the police are trying to restore order. To make people feel safe in their home, neighborhoods and businesses. Business, private property, and public property are being damaged. Businesses, and individuals are being robbed. Under that climate some decides to make a "joke."
However, here is the problem. The prosecutors will try to convince the magistrate that the individual was capable, and that that individual knew it was wrong. The prosecutor will present the evidence of the "deleted" Facebook page. The prosecutor as has the hard evidence that other riots have broken out. Now, it is your lawyers job to convince the magistrate that it was only a sick joke, and their was no real intention.
It isn't the slowest, or the dumb that get caught, just those that the police get "lucky" with.