Amex Policy within the States is 60 days - which is crap considering how much people rave about Amex customer service. The only card that I have found which has an unlimited dispute window is Discovercard but require documentation. However, it still remains to be seen whether their unlimited dispute promise has any teeth or not.
I just spoke with Discover today, and they said their chargeback/dispute window is 90 days.
That's not what I have recorded on audio. I called on June 3rd and they gave me a much different answer.