I don't travel much but have heard lots of horror stories about entering into the USA. What exactly can the border guards check in your smart phone when entering the USA? I use mine a lot and it's connected to online banking, email, social media and google drive. I'm assuming he can't check things like online banking, but is he really allowed to go through email? I text people I'm close to like my girl friend and I'm really not comfortable with a stranger going through it. Can I put on app specific passwords? Can you watch the border guard check your phone?
Border agents can’t search your phone unless they have reason to believe you committed a crime due to a recent court ruling.
From the Guardian:
US border authorities cannot search the cellphones of travelers without having some reason to believe a particular traveler has committed a crime, a federal appeals court ruled on Wednesday.
This decision is binding only within the jurisdiction of the US Court of Appeals, Fourth Circuit: Maryland, Virginia, West Virginia, North Carolina, and South Carolina.