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.
The Ohio Jury Oath goes like this:
“Do you swear or affirm that you will diligently inquire into and carefully deliberate all matters between the State of Ohio and the defendant (giving the defendant’s name)? Do you swear or affirm you will do this to the best of your skill and understanding, without bias or prejudice? So help you God.”
"All matters" includes the nature and character of the law which the defendant is charged with violating. In New Hampshire, the oath is:
You solemnly swear or affirm that you will carefully consider the evidence and the law presented to you in this case and that you will deliver a fair and true verdict as to the charge or charges against the defendant. So help you God.
Returning a guilty verdict when a juror believes that applying the letter of the law in that manner would unfair, a miscarriage of justice, then THAT would be the violation of the jury oath.
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.
And just how many OJ cases have there been in the last 16 years? In the last 100? You're worried about a stampede of unicorns while I'm concerned with the unfair and abusive application of an unjust law that the jury has the power to stop.