If I'm in a crowd in the presence of a number of other law breakers, why would I think that I couldn't ever be temporarily detained? I mean, yes, it shouldn't be indefinite and there shouldn't be a high bar to clear to prove actual innocence, but we have process for this. I can be arrested without much provocation at all. I then have to be charged, I have the opportunity to enter a plea, get bail, and then I get a trial. All of that can (and does) happen to people who are legitimately innocent.