The U.S. Federal Reserve employs expansionary policies whenever it lowers the benchmark fed funds rate or discount rate or when it buys Treasury bonds on the open market, thereby injecting capital directly into the economy.
Expansionary Policy is a useful tool for managing low-growth periods in the business cycle, but it also comes with risks. First and foremost, economists must know when to expand the money supply to avoid causing side effects like high inflation. There is also a time lag between when a policy move is made (whether expansionary or contractionary) and when it works its way through the economy. This makes up-to-the-minute analysis nearly impossible, even for the most seasoned economists. And finally, prudent central bankers and legislators must know when to halt money supply growth or even reverse course and switch to a contractionary policy.