Here's the thing, I know exactly what rules I'd ordinarily need to follow in order to enter the United States. It's a mental checklist when coming from Canada:

Here's the thing, I know exactly what rules I'd ordinarily need to follow in order to enter the United States. It's a mental checklist when coming from Canada: 1) am I carrying any contraband? Drugs, guns, undeclared currency or goods, etc. 2) Can I show that I can support myself during my stay? Do I have a return ticket? Enough cash? Compared to these requirements these searches are completely opaque. If I'm asked to hand over my device I'm thinking: 1) How much is the agent going to access? Is s/he going to see an NSFW pic I emailed to the gf? 2) Are there any legitimate protections keeping them from logging into my social media accounts and going through my history? 3) Is there any recourse if they see me making a "420" joke ten years ago on Facebook and denying me entry? There should be clear criteria admissibility that also serves to protect your privacy.