Why is Bill Ayers not in jail?
Before the trial, defense lawyers alleged that their offices had
been broken into and their papers and case notes searched. It was
also discovered that the U.S. government had illegally bugged some
of the defendants. (This was happening at the same time as
Watergate.) In 1975, the U.S. government decided to drop the
charges "in the interest of national security."
Source: "Former federal prosecutor decries Williams Ayers" See link below.