What do the FISA Courts do?

The Fisa Courts were created in 1978 to allow the government to conduct acts of surveillance agst. certain individuals and groups by permission by this special court.  The Courts rule in matters of National security without exposing what types of surveillance tracking were committed.  One local conservative said tapping phones have gone on since the Truman administration.  If we have a whole apparatus of government that is shielded to the American public on the nuts and bolts of thier operation, who is really aware anyway and what really can they squeeze out of the average Joe who is likely not involved in terrorist activities?  That and more, about Wisconsin 537% payday loans.