Indeed. My impression is that American citizens are guaranteed eventual re-entry into the country, though perhaps after some detention time and without their ga

Indeed. My impression is that American citizens are guaranteed eventual re-entry into the country, though perhaps after some detention time and without their gadgets. So an American can refuse to give up passwords as a matter of principle. Non-citizens, even green card holders, don't have that guarantee. I don't think you have the right to a lawyer before CBP puts you on a plane flight back to your point of origin. So if you decide to be principled and claim that you have the right to withhold your data from searches, you're doing so with the risk of having to continue your life elsewhere.