Originally Posted by Aguila Blanca
... it is supposed to work just the way you don't think it can't work, which is that the presumption is innocence rather than guilt, and the cop has to have something more than just a suspicion...
You might think that's how it's supposed to work, but on what basis? And indeed, in the real world it does not. The Fourth Amendment protects against unreasonable searches and seizures, and the courts have consistently found that a detention for investigation based on a reasonably articulable suspicion is reasonable.
This isn't a question of the presumption of innocence. That is a rule of evidence that applies in court. It means that it is the persecution's burden to prove in court the defendant's guilty.