And it doesn’t permit the jury to categorically state that the law is invalid. That is a matter of law, not fact, and juries are for finding facts.
@OceanderNot
just facts, though that's what judges would like you to think.
In the Pennsylvania Constitution, Article I, Section 7, it states: "... and in all indictments for libels the jury shall have the right to determine
the law and the facts, under the direction of the court,
as in other cases." [Bolding is mine.]
Note that it says that the jury is not just to determine the facts, but also the law. And although this section is obviously directed primarily at the Zenger case, those last words note that it doesn't just apply to libel.
This is why I've never been able to sit on a jury. When, during
voir dire, we're asked whether we'll follow the judge's directions, and the judge's directions are given as incomplete, I write on the questionnaire that I will follow the Pennsylvania Constitution. Judges (in PA, at least) don't like having to follow the law.