Originally Posted by
KLflyerRalph
As a non-US citizen,
Can I refuse answering ridiculous, irrelevant questions by CBP?
Yes, but you may be subject to additional inspection and may even be refused admission to the country.
Can I refuse any questions by TSA?
Legally, yes, but practically you'll be in for a hassle.
Can TSA ask me for other things than my BP/ID (be it documents or questions) and do I have to answer/provide even though I provided BP/ID?
TSA can ask for whatever they want. You can say, "no."
Does TSA have the right to inspect (as in read) documents in my hand luggage?
No, though if in the process of inspecting for weapons/explosives/incendiaries, they read documents in your possession, what they read can be admitted as evidence against you.
Can CBP force me to unlock my phone for inspection?
"Force"? No. However, they can confiscate your phone and send it for analysis if you don't cooperate.
Basically, which rights as far as privacy/keeping silent are concerned, differ for non-US citizens vs. US citizens.
None -- the 4th and 5th Amendments apply to "people," not just "US citizens." However, certain 4th Amendment rights don't pertain at the borders or quasi-borders, i.e. airports.
I understand CBP can deny me entry if I refuse to answer questions. But to I have to respond to EVERYTHING?
No one can force you to respond to anything. However, as you note, you can be denied admission and, if probable cause exists, arrested.
Which demands does TSA/CBP 'often' ask (to foreigners) which they aren't able to do by law?
Not being a foreigner, I don't know. However, TSA and CBP frequently overstep their lawful authority.