The reason Jury Nullification isn't used is because the DAs, judges and attorneys do not WANT it used. It allows the citizens to basically throw out any law they feel is bad or unwarranted. Similar to what happened with prohibition. Imagine if every time they brought someone up on marijuana charges and the jury voted Not guilty. How long before they just gave up on trying to prosecute that? Or steroids, or ephedra, or MDMA or...
The fact is, if you talk about or acknowledge Jury Nullification at pre-screen or at the time of jury selection you will be promptly relieved from jury duty.
If what you say is true about drug use, why isn't there the bandwagon to ban Tobacco, and alcohol??? Those DRUGS effect people also.