The Doomsday Book is largely a collection of legal opinions compiled by the New York Federal Reserve (and long kept secret) that defines its authority to respond to financial crises. Thanks to a successful Freedom of Information Act request by the author, this essay discloses the Doomsday Book’s contents and puts them into context. The document reveals that instead of adhering strictly to clear legislative boundaries to justify its actions during financial crises, the Fed seems to ground many of its decisions in the New York Fed’s belief in the agency’s discretionary authority.