Accountability.

http://en.wikipedia.org/wiki/Federal_Reserve_System

Accountability

The Board of Governors of the Federal Reserve System, the Federal Reserve banks, and the individual member banks undergo regular audits by the GAO and an outside auditor. GAO audits are limited and do not cover "most of the Fed’s monetary policy actions or decisions, including discount window lending (direct loans to financial institutions), open-market operations and any other transactions made under the direction of the Federal Open Market Committee" ...[nor may the GAO audit] "dealings with foreign governments and other central banks."Various statutory changes, including the Federal Reserve Transparency Act, have been proposed to broaden the scope of the audits.