At a systemic level, its validity is kind of irrelevant because any time you ask a human being to judge whether a law is broken, there’s no way to prevent them from saying no because they don’t agree with the law. Prosecutors and judges can try to weed out jurors who will answer based on their conscience rather than just facts, but they can’t eliminate the possibility.

On a personal level, I can recognize nullification is easy to abuse, but if I’m on a jury and I’m asked to convict someone of breaking an unjust law, I could not in good conscience sacrifice that person’s freedom just because another juror in a different trial could do the same thing for bad reasons.

As the question of whether nullification should be promoted, I think it should, because people have a right to know how their government works as part of their right to choose how it works. A government whose most fundamental mechanisms can’t hold up to public security is ipso facto authoritarian and undemocratic.