I think it's actually part of the deal when they give you the job, if not specifically then it is certainly alluded to.
You'd think that, but it's not actually what happens a lot of the time, in my understanding. John Oliver did a whole show about it.
Why wouldn't they have that information easily available on file then? Why the whole detaining process for 4 hours when it should have been something easily checked?
4 hours was fast, sheesh. You instatwitter generation... :)