cashiers checks as banknotes

when is a cashiers check a banknote? When someone "important" says it is. It used to be that many banks would print their own banknotes. (sounds like a great job) But confidence in a bank note is only as strong as confidence in the issuer. Better to be printed by th government I think.

I'd like to be able to swap a note for the amount in gold, but that was in the old days I guess.