When I first heard about the NY Fed's Doomsday book, my initial thought was, "Wow, they've got a comprehensive survey of land titles, so MERS really isn't an issue!" Then I realized it was a Doomsday book, not a Domesday book. Apparently the Doomsday book is some sort of "in case of emergency" do-it-yourself bailouts manual that outlines the steps the NY Fed believes it can legally take to stave off economic Armageddon.
I'm rather puzzled by the NY Fed's claim that it should be kept under seal. I guess we'll find out more of the Fed's reasoning soon enough, but it hardly seems to be particularly sensitive of secret information. This isn't the Coca-Cola recipe or some sort of trade secret. It's hard to believe that we didn't see the full panoply of the Fed's bailout powers on display in 2008, and perhaps then some. (A colleague has suggested that they might be developing some sort of secret, stress-tested, boilerplate clad bailout machine in the basement of the NY Fed. Of course such a bailoutbot would exercise its own free-living-will. Its only vulnerability would be following a haircut.)
The fact that the Doomsday book apparently contains legal advice is not a seal issue--that's a privilege issue. Once that privilege is waived (I'm guessing it has been), I can't see why the fact that the document includes legal advice presents cause for remaining under seal.