But what are the guidelines for labeling someone an extremist? And where is the line? Should we start loc
king up Christians who preach on the corner yelling about how soldiers are going to hell? Are they extremists?
You can't pool all these people together and throw them in jail for a "suspected extremism". You also can't have spies watching all these people all the time.
Because they are suspected extremists. Imagine if the standard for being an extremist in any other religion was so low. How many Christians, Hassidic Jews, devout Buddhists, Hinduists would be placed on a list. All those groups (With maybe the exception of Buddhists) have killed people.
The real problem is that once you just allow the government to pick and choose who is an extremist and who isn't, the second a new administration comes in they could easily target a religious or political group without evidence.
And you know this how? Are you part of MI5 or MI6? Many of them aren't even under active investigation. They may have simply been suspected for opening an obscure twitter link and then been moved to the closed investigation category that the Manchester bomber was open. The criteria for extremist under MI5 is not public information so we really have no idea.
It isn't "justice" when a full 1%(2,200,000 in jail and over 4 million on probation and parole) of the adults in your country are locked up, and there is blatant racism in that system, with Latinos and Blacks being locked up for petty drug offenses even though white people are more likely to be carrying those drugs (politifact source).
General Address:
"On Friday security sources confirmed a further 20,000 individuals were said to have been considered “subjects of interest” in the past, although the period the figures cover is unclear." - The Independent.
Now, you might say, "Well the Manchester attacker was part of this 'past' list." This is true, but what many have failed to mention is that 13 attacks were foiled in the past year. It really comes down to the fact that you can't lock up people who you "think" are bad guys. Once you do that, democracy follows suit and goes down the tubes.