ACA is suing Goldman over the ABACUS deal that blew up in their face and in which Paulson (John, not Hank) was involved. If you remember, this was the deal over which the SEC sued as well, and "settled." The argument at the time was that it would be very difficult to prove fraudulent intent, and therefore the settlement (without admission of guilt, of course) was "in the best interest of everyone."
Well, now in this complaint ACA alleges that not only were they not told the instrument was created due to someone's short interest, they were explicitly told by Goldman that Paulson intended to be long!
If proof of this this exists, it's black-letter proof of fraud folks:
Read the rest here