I’ve been on FR long enough to know that someone will correct me if I’m wrong but jury nullification involves more than just a single juror - thus “jury nullification” and not “juror nullification”. A single juror refusing to convict someone guilty under the letter of the law would result in a hung jury, a mistrial, and subsequent retrial of the defendant. In order for jury nullification to occur, the juror would have to convince all his peers to vote not guilty in the face of the law. IOW, the job would be to put the unjust law on trial within the jury room without prompting someone to “squeal” to the judge.
An alternate choice is to have enough people in the general population unwilling to convict so that every jury will be a hung jury. Eventually the government just gives up prosecuting in those cases. The only law I can think of off the top of my head like that were the fugitive slave acts in the North before the Civil War. There were enough abolitionists around that it was hard to find twelve men for a jury without one or two guaranteed to vote not guilty no matter what.
I've been called for three juries. One the first they got the 12 plus alternates before they got to me. On the second, the jurors felt the prosecutor overcharged by going for a felony on what should probably have been a misdemeanor. We were instructed to just judge the facts, not the law, and to not consider the punishment. Once we got back to the jury room the first question was "the defendant can get a year in jail for that?" Combining that with a weak case to begin with and we came back 12-0 not guilty.
On the third jury we were asked in voir dire if anyone heard about jury nullification. I raised my hand and the prosecutor asked me what I knew. I told him that it was the duty (I didn't say right) of the jury to judge both the facts and the law. I went into further detail, but was stopped before I got to the Penn case and English common law (By the time I raised my hand I figured I was going home anyway, so I figured I might as well educate the remaining jurors). The prosecutor made a smartass remark that maybe I was on the wrong side of the rail. When the 12 jurors who were picked were announced I wasn't on it. What a surprise. The case was about someone taking a swing at some government official on his doorstep, so I didn't see it as a major rights case where nullification might matter. If it had been a 2nd amendment case, I hope that I would have been able to keep my hand down or at least give a much less definitive answer about what jury nullification was.