I thought individuals acting in the line of duty were immune from this kind of lawsuit. I had to fire a guy once and he tried to sue me. The U.S. Attorneys Office took care of it forthwith.
LEOs do have some immunity, but a plaintiff can get around it if he can show that the LEO’s conduct was particularly egregious. I usually don’t find Wikipedia to be a good source for anything controversial, but it has a pretty good explanation: http://en.wikipedia.org/wiki/Qualified_immunity.