The jury's job is not to say whether the law is fair- that is a matter that goes through the appeals process and lands on the desk of the appropriate supreme court.
The jury is there to say yea or nay as to whether there is ample evidence, beyond reasonable doubt, that you have broken the law.
If you want to change the law, you could get caught and then TRY to go appeal it (good luck- you'd need deep pockets, a GREAT attorney, as in, his business card says, 'Joe Schmoe The Great, ESQ, and some serious luck that the judge won't just deny the appeal)... or you could just lobby your elected officials hard...

What you are talking about would be considered a hung jury and result in a mistrial.