It's not that, it's more that you want to get in and you have to make sure they don't have a reason to say no. They have something you want (access) and you don't have anything they'd want to grant that. So as soon as you make it hard you're bound to have trouble.

It's illegal for them to deny entry to U.S. citizens.

I'm the author of OP's post. Can you provide me more information about this? I've always wondered if that was the case, but I was once given a lengthy interview in the Amsterdam airport on my way to DEFCON last year, which gave the opposite impression.

If you are a US citizen, US immigration cannot legally refuse you entry. They can make your life miserable (via private questioning, etc.), and US CBP can also make your life miserable (going through all your stuff, questioning you at length, etc.), but they are legally required to allow you into the US if you are a citizen. If they can pin something illegal on you, they can of course detain you and refer you to local or federal authorities, but they must (as a part of that) allow you back into the country. They can't force you to stay in the international zone at the airport, and can't send you to another country.

Now, this only applies to US citizens returning to the US. A US citizen arriving, for example, at Amsterdam, can certainly be turned away for any reason whatsoever.

Thanks for this information. In my example, I was departing Amsterdam for the U.S.

There is a big difference between upholding your rights of privacy while being respectful to the border agents and while being a smart-Aleck. You do not have to do everything they say, but you can stand your ground without trying to antagonize them unnecessarily.

Not really. There is no right to privacy at the U.S. border, so any "upholding" or "stand your ground" is, actually, being a smart aleck / unnecessary antagonization.

Do you not see the difference between being polite and being obnoxious when you decline the search of a device in your possession? Indeed, the border agents can refuse to let you enter the country either way, but the probability of that happening would probably differ in the two cases.

No, I don't see the difference, because people crossing the U.S. border simply don't have any right to decline searches:

https://en.wikipedia.org/wiki/Border_search_exception

You can decline the search in which case they can decline to let you in the country. The EFF FAQ has more details.

Interesting - I don't suppose you have a link to relevant part of this FAQ?

Sorry, I was on mobile when writing the previous comment.

Here is the lengthy document I remember: https://www.eff.org/document/defending-privacy-us-border-gui...

They can demand a password from you, you can refuse to give it, and they can then decide not to let you in the country. Being polite and respectful in your refusal to share an encryption key can mean less trouble.

A point that might have caused confusion: they can seize your device. The document does not specify what happens if you decline to give the device (as in whether you are arrested or simply declined entry to the country). As far as I understand the references, courts have not had to decide on this question yet.

Customs is different than dealing with the police. There is no liberty at any border.