The Supreme Court has reserved immunity in most cases involving prosecutors.   Many of the circuit courts have, also.  The 7th Circuit, however, has carved out a wee nitch that might allow those wronged by the legal system to fight back.  The Washington Post has investigated and analyzed major arguments and cases in an article worth reading:

http://www.washingtonpost.com/news/opinions/wp/2014/01/30/7th-circuit-pokes-a-hole-in-prosecutorial-immunity/