Jury Nullification has a long history extending back before the United States existed and as a part of British Common Law.

I don't think you'll find many lawyers willing to make the argument for nullification from the bench. A lawyer friend explained to me that practicing criminal defense law was like being an island in a sea. If you piss off DA's and judges you'll find your island getting smaller or some such metaphor or simile.

It's more important to know about nullification when you're serving on a jury. That's when and where you can make a difference.

Anyways, if you'd like to learn more about jury nullification, check out:

Fully Informed Jury Association

They've got pamphlets and lots of other material