Are you sure? In Germany:
* Can the state police demand that you open a bag for inspection on a train?
* Can you be detained at length (for instance, removed to a police station) if you're asked to identify yourself and don't have documentation?
* Are the police under any circumstances permitted to randomly stop and search cars?
* Can the police check your pockets during a pat-down search for weapons?
Each of these is something for which US jurisprudence has issued decisive and binding decisions (no, absent probable cause they can document and justify on the stand, they can't open your bag; no, unless they arrest you for an actual crime, they can't take you to a police station; no, under most circumstances the police can't even pull you over unless you've committed a "primary" offense, and cannot absent probable cause of an actual crime search your car; no, the police in the US can't demand to see the contents of your pockets).
Incidentally, you have the same protection under the 4th Amendment as a German citizen in the US as I do as someone born in Chicago. I assume that's true vice-versa in Germany as well.
The bag issue is what got me; Swiss police rifled through my bag. I was not the only person in the train car that happened to, so I'm doubting I was simply selected for it as a noncitizen --- not that that should matter.
