> hold me briefly

You might want to consider whether your definition and the government's definition of "briefly" agrees.

For example Carlos Rios, a naturalized U.S. citizen was held for a week before being released. Peter Sean Brown, another U.S. citizen born in Philadelphia was detained for three weeks. Source: https://www.propublica.org/article/more-americans-will-be-ca...

Neither of those are even related to border control, let alone one's ability to refuse to unlock one's phone while going through it.

I don't know what to say about the naivety here. I guess I should say good luck, because you'll need it to hope that your illegal detention is brief.

You are assuming that they follow the rules. Have you been reading the news lately? Rules are for losers.

So far they are, for citizens. The worst case I've heard of was a citizen who was held by ICE for a few hours because they didn't believe him. Which, don't get me wrong, is bad given the racist underpinnings of it, but not something that worries me in and of itself. And yeah, they've gone so far as to deport US citizens from time to time over the years, but it's not anything like systematic.

They're not refusing entry or holding citizens indefinitely for refusing to unlock their phones at the border. Maybe they will, but until it starts, what I said holds.

When I say “they”, I’m referring to the people ICE reports to. Precedent and rules don’t constrain them, so what happened in past years seems irrelevant.