Originally Posted by SeaProf

I'm a US citizen and have used it a couple times, both in YVR. The first time they weren't actually set up with the equipment to read it, so they waved me through straight away. The second time I walked straight up to the desk as no one was in front of me. Went through quickly but then got pulled aside for additional screening by American customs. I'm guessing they were bored and I was an easy target given I was the only person going through that line.