Your efforts are heroic and commendable, and are absolutely essential, but if someone else had undertaken this work, and you instead had found yourself on a jury of someone charged with violating this law which you KNEW to be unconstitutional, would you still have voted to CONVICT HIM?
If you would have, then what's the point of a jury trial? Why not just feed the facts into a computer and let it flash a green or red light accordingly?
Working to overturn bad law can be done AT THE SAME TIME as refusing to convict someone of violating it. The two are not mutually exclusive as you suggest.
The JURY is the CONSCIENCE of the community. It is the PEOPLE's VETO. If you refuse to apply your common sense and your innate sense of justice when rendering a verdict, than you might as well have written the abusive, tyrannical, unjust, and unconstitutional law yourself.
The very first thing even a marginally competent criminal defense attorney would do in the case of an unjust, unconstitutional, or unconstitutionally applied law would be to interpose an appropriate plea or demurrer (depending upon the criminal procedure laws of the jurisdiction).
At least in this state, a criminal defendant has numerous grounds on which a pretrial appeal may be taken.
But let's assume, arguendo as they say, that some poor sap somehow got a completely incompetent defense attorney who somehow neglected to interpose the proper plea and/or take a pretrial appeal (and despite strong hints from the judge because they don't like being reversed), and THEN didn't manage to assert a defense or present evidence that gave the jury an option of acquittal.
In such a highly improbable case, the law still has multiple remedies. A new attorney on appeal (paid for, by the way, if the defendant is indigent) may file (1) a motion for new trial asserting ineffective assistance of counsel under Strickland v. United States, or (2) an extraordinary motion for new trial or habeas petition asserting the same.
If there is any factual basis for acquittal, which any decent defense attorney can provide, then the jury will and should seize on it. It doesn't take very much to support a jury verdict of acquittal.
But if, theoretically speaking, somehow there is no factual basis for acquittal and the jury can't imagine one, then turning the jurors into unelected legislators is not the answer. Making up an acquittal out of thin air gives you the likes of O.J., only worse since that jury had some arguable facts on which to hang its hat.
As the case law hereabouts states, even though a jury generally has an absolute right to acquit, if the evidence is overwhelming and unopposed then it is their duty to convict.