Originally Posted by
PeterNem
You would head straight through security if traveling on an ESTA and you had already printed your boarding pass, it's just when there's a visa involved the carrier has to check your paperwork first.
My experience is different: going to the US with an ESTA and boarding pass ready, trying to enter T5 security from landside, I was sent back to the desk to confirm (by scanning the passport and a few keystrokes) that the passport I was carrying matched the one I had checked in online with.