I am not a lawyer, though I am a US citizen. First, it's the fourth amendment that protects against unreasonable search. Fifth amendment is protection against

I am not a lawyer, though I am a US citizen. First, it's the fourth amendment that protects against unreasonable search. Fifth amendment is protection against self-incrimination. My understanding is that fourth amendment protections effectively do not apply at the border [1] because the border is inherently a reasonable place to search people. In regards to being compelled to unlock your phone, CBP maintains the position [2] that in order to uphold their duties they're inherently able to compel you. Anecdotally, if you don't unlock your device, they may (a) confiscate it (and possibly apply all sorts of cracking tech to it), or (b) refuse you entry. That said, a random law firm [3] cites that you can withhold a password-based lock, but CBP can compel you to provide biometric unlocking [3]. To me, this is a case of https://xkcd.com/538/ https://xkcd.com/538/ ; you may have a legal basis to refuse, but in the current iteration of the administration I find it unlikely that it would be a positive experience if you were to stand on it. (Not that CBP is going to beat you with a pipe wrench, but if they want in your phone, they're gonna get in your phone.) [1] https://law.justia.com/constitution/us/amendment-04/19-border-searches.html https://law.justia.com/constitution/us/amendment-04/19-borde... [2] https://www.cbp.gov/travel/cbp-search-authority/border-search-electronic-devices https://www.cbp.gov/travel/cbp-search-authority/border-searc... [3] https://borderslawfirm.com/border-search-computers/ https://borderslawfirm.com/border-search-computers/