What is the RICO act?

The acronym RICO stands for Racketeer Influenced and
Corrupt Organization.  The law is one that is meant to give law enforcement officials a
good way to prosecute members of organized crime organizations (like the
Mafia).

Basically, the important thing about this law is
that it allows prosecutors to charge someone (notably a mafia boss) witha crime even if
he never participated in any specifically illegal actions such as extortion or promotion
of prostitution.  The idea is that because he is a part of this illegal organization, he
is a criminal by that very fact.

This law, then, allows the
government to charge and convict people for being members of organized crime groups even
if they cannot be proved to have committed any specific crimes.