For the last 100 years or so, the following rules work well.

As a juror, never say you know what it is or you'll be expelled from the jury.
As an attorney, you may be expelled from the case for bringing it up.
As a defendant, mentioning it in court will really piss off the judge, and the jury will be instructed to ignore your statement.

Even when "REMEMBER JURY NULLIFICATION" stickers on placed on things and shown to juries, those will be edited out.

The effective method using Nullification would be to have an educated jury, sadly, you won't get one. Your best luck will be living in an area of well educated people with a low population.