So when will you jury nullify? Most defendants won't stand before their peers, won't face a judge beyond cursory rubber stamping, and won't get good representation (public defender funding is cut year upon year, some public defenders take on over 500 cases a year now).
The US justice system is utterly broken, beyond repair. It is a revenge system (not rehabilitation), with little justice to be had except of the wealthy (who will get off scott free), overly politicized, overly money orientated (e.g. spend a year in jail unless you have $100K), and has purposely high maximum sentences to force even innocent people to take a plea (which they often do [0]).
I can think of few other countries which has a criminal justice system as bad as the US, and unfortunately when I start naming them they're not really the type of states the US wants to be associated with.
[0] http://www.fhsulaw.com/Legal-Articles/Plea-Bargain-Sentences...
Sinnigen took a plea deal; there was no jury involved. If somebody said something incriminating via Facebook, the trial against that person wouldn't be allowed to mention prosecutorial malfeasance in an unrelated case.
You can fight back by refusing to convict defendants who were prosecuted using immoral or illegal methods. And remember, a juror has no way of knowing if the police/FBI/DEA lied to the court throughout the process, behavior which has been heavily documented in general.