I think its a general doubt if the defendant is guilty. You can break that into (1) doubt about the facts being sufficient, or (2) whether the facts presented are true. I don't think these days that the doubt would cover the validity of the law
it sounds like Prof. Nesson doesn't really believe in any numerical figure either. He referred to belief of guilt as a "feeling" instead. This fact is worrying, since jurors' feelings about guilt are so often based off of factors not related to the defendant's actions
In the case where the 17-yo kid carried a gun without registration: we agreed that he had violated the statute but we also agreed that he was not guilty? Why was he not guilty? we had doubts that he had transgressed against societal standards or that he had hurt his community.
I find an obsession with removing feelings far more unreliable and unrealistic - - because "pure concepts" of rationality/logic/neutrality/objectivity are fictions that have been used to propel mass incarceration of Black/Latinx people. Reckoning with inevitable feelings of all who partake in the process is more honest and realistic
Thinking about reasonable doubt as "an abiding conviction in the truth of the charge" as opposed to "99/100" would seem to require the jury to confront, more directly, the moral/ethical implications of depriving an individual of liberty
I am sympathetic to the idea that the degree of certainty required for reasonable doubt should be able to fluctuate in response to the circumstances and the punishment. Although this allows for unpredictability, as a juror, I would have a higher standard for crimes that are inherently easier to prove and carry higher punishments.
love that @Moon mentioned the gun permit case. It helps show that there's more to the jury's calculus than showing that someone checked off the boxes of a statute beyond a reasonable doubt. it gets at the whole "feeling" aspect of jury decisions that Prof. Nesson has been pushing on. Unfortunately, these "feelings" also cut the other way and disproportionately harm Black/Latinx defendants, as @Callisto mentioned above