Props to the defendant for volunteering as a test case. He should've powered off his phone before he went through customs, or better yet traveled with a burner phone.
It doesn't matter if the feds are doing something wrong... if you interfere or destroy potential evidence, rather than simply recite your 5th and 6th amendment rights, you've put yourself in a whole new ball game.
He probably would've been fine if he'd maintained his refusal contingent on talking to a lawyer first. They might not have even attempted to crack the phone, and if they had, he'd have a better chance of getting the contents thrown out than he has now of fighting the destruction of evidence charge. The two issues are largely separate, unless a court decides the detention and attempted search were so egregious that they negate his separate, intentional act of wiping his phone when he was being detained.
We might wish for a mobile device to be a mobile castle immune from any [request for] search or seizure without a warrant, but that hasn't been established in case law, and everything else crossing the border (except what's diplomatically immune) is subject to some warrantless scrutiny.
So everything is potential evidence, even any memory in your brain, were're soon be at Johnny Mnemonic situation here.
The exceptions I know of are things like:
- In some situations you have to ID yourself (not just when you're driving, but that's the usual case, where they have legal authority to ID you, and if you don't have ID you have to provide the equivalent from memory so they can check your identity.)
- Face and Fingerprint unlocks are not things in your mind, they're not testimony, therefore you can be compelled to provide them, though usually by court order. If a cop in the field is forcing you to face- or fingerprint-unlock your phone, that might not be allowed.
- In a few jurisdictions, if it's a "foregone conclusion" what's on your phone, i.e. they know from other threads of the investigation what's on it, but it's just encrypted, they might be able to force you to unlock it in that case, but that's through a court order not during a field investigation.
My Samsung phone has a feature to automatically format the device if the wrong code is entered X number of times, and I have security software that would let me wipe it remotely (if it still had internet access) so this whole situation brings up a lot of questions about features like this.
EDIT More discussion about it here, but it's quite technical. I was a bit confused about the rate limiting stuff and etc.
GrapheneOS protections against data extraction from locked devices - HN Post https://news.ycombinator.com/item?id=49055169