That constitutes de facto detention and yes, there's absolutely something that governs it. Unfortunately ICE/CBP has policies [1] in place to require the phone

That constitutes de facto detention and yes, there's absolutely something that governs it. Unfortunately ICE/CBP has policies [1] in place to require the phone's password that they believe are legitimate per 8 USC § 1357(a) (3). It's likely that only a court ruling weighing the policy regarding this statute against the bill of rights would make them change. [1] https://www.dhs.gov/xlibrary/assets/ice_border_search_electronic_devices.pdf https://www.dhs.gov/xlibrary/assets/ice_border_search_electr...