From its inception in 1913, the Federal Reserve's structure was designed to insulate monetary policy from day-to-day politics. The founders recognized that sound money and financial stability require a long-term view that elected officials—facing the next election cycle—cannot reliably provide.
The Fed's independence is not about placing it "above democracy"—the Fed is ultimately accountable to Congress's mandates (stable prices, maximum employment, moderate long-term interest rates). Rather, it's about ensuring that day-to-day decisions are made for the long-term health of the economy, shielded from short-term political manipulation.
The Dual Mandate
The Federal Reserve Act, as amended by the Humphrey-Hawkins Act of 1978, establishes the Fed's mandate: to promote effectively the goals of maximum employment, stable prices, and moderate long-term interest rates. This mandate comes from Congress, and the Fed must regularly report to Congress on its progress. But how the Fed achieves these goals is left to the Fed's expert judgment.