The Foreign Intelligence Surveillance Agency, or FISA for short, is a U.S. Federal court that oversees surveillance against possible spies in the United States. In order to actually begin wiretapping and other surveillance, a granted surveillance warrant is required. Although there are open conversations about FISA, it is a secret court, so the public is unaware of their hearings. These hearings can also happen at anytime because there is always an "on-call" judge, so they can expect a call day or night.