Originally Posted by
warakorn
The advantage of pre-clearance in Dublin is that US immigration can deny you without actually formally denying you.
The guy had no ticket leaving the North American continent. Thats a clear case of not granting access to the US via the Visa Waiver Program.
Actually, the airline should have denied him issueing boarding cards without an onward ticket. He should not have gotten to the US immigration guys in the first place.
I travel on one way tickets all the time and all airlines do is make me sign a form stating that if I am refused entry they aren't responsible. I've only been asked for a proof of onward travel by an immigration officer once and it was in the UK.