There's one argument against this sort of treatment that I'm surprised I've never heard though.
I think everyone at this point agrees that the only way to stop terrorist attacks is to have good intelligence. I also think everyone agrees that good intelligence is dependant on the public giving notice to the police when they see something suspicious. Probably no one questions that for people to talk to the police, they have to trust the police. And it should be obvious that the most likely witnesses to something like preparations for an islamist terror plot, would be other muslims. Be it family, 'friends', neighbours, people going to the same mosque, etc.
Now, would you turn over your neighbour to the police if you saw something mildly suspect, if you know this could result in him getting abducted, held without trial for years, and quite possibly even tortured?
