Originally Posted by
gonebabygone
I was going through US customs in YUL in January, and while the agent was looking over my passport, I pulled out my phone to check the time. The guy yelled at me and, I kid you not, threatened to detain me and make me miss my flight! All for *looking* at my cell phone! Ahh, power trips.
This is an interesting situation. US pre-clearance is just that, and the land you're standing on continues to be Canadian soil.
So a polite "What Canadian Law prohibits the use of my phone" to a US CBP officer; will shut that down immediately.