What is proof beyond a reasonable doubt?

As I finish up a few long-standing projects on knowledge (check out my draft monograph!) I'm hoping to start exploring a few new-for-me areas. In recent years my philosophical discussions on this blog have been relatively esoteric, trying out a new objection to so-and-so's third paper on such-and-such; when I was in grad school I used it as an early thinking-out-loud forum about more basic stuff. If I can swallow my pride enough, I may return to that form over the next several months. One area I'm quite ignorant and naive—but also curious—about is law. In particular, I'm curious about how legal concepts like evidence and testimony interact with epistemological concepts like evidence and testimony. I'm a complete novice in this field, so if I'm overlooking things that seem totally obvious to any readers, I'd be grateful to have it pointed out, especially if it comes along with reading advice.

One of my entry-points into the literature here is my UBC colleague John Woods's book Is Legal Reasoning Rational: An Introduction to the Epistemology of Law. (I'm maybe 40% of the way through a first read of it now.) Here's one thing I've found interesting so far. Woods writes, on p. 103:

Spike cannot be convicted unless a jury unanimously finds that his guilt has been proved beyond a reasonable doubt. Certainty beyond a reasonable doubt is sometimes said to be moral certainty. Under either name, as Gifis writes, it is a conviction based on persuasive reasons and excluding doubts that a contrary conclusion can exist. This is much too strong a formulation. There is plenty of case law that allows for conviction even in the face of a perfectly reasonable case to the contrary, recognized as such by the jury. On an alternative formulation of the standard. A juror is said to be morally certain of a fact when he or she would act in reliance upon its truth in matters of greatest importance to himself or herself. Although better, this appears to omit the essential requirement of criminal proof that this readiness to act, this moral certainty, be grounded in the juror's belief that the burden of criminal proof has been met. In other words, it seems not to be sufficient for criminal conviction that a juror be in a state of moral certainty of the accused's guilt. It also matters how he came to be in that state. 

So we have these notions:

• Proof beyond a reasonable doubt
• Certainty beyond a reasonable doubt
• A juror's being in a state of moral certainty

Woods slides between the first two without comment. Maybe the thought is that there is this tight relationship: proofs establish certainty. (In logic or mathematics, this seems plausible—if I have a proof of something, then it is certain for me.) But as Woods points out, it's another matter whether my psychology reflects this certainty. I might have a proof but doubt anyway; or I might be irrationally certain, even absent a proof.

I wish Woods had explained further what he had in mind when he discusses appropriate conviction in the face of 'a perfectly reasonable case to the contrary'. (I am not sure who Gifis is—I don't see a citation.) Can there be 'perfectly reasonable' cases that have been proven not to be the case? If 'provability beyond a reasonable doubt' is closed under deduction, then it seems like there must be. (If it's been proven beyond a reasonable doubt that Jones committed the crime, then it's provable beyond a reasonable doubt that Jones wasn't framed.)

The alternative formulation mentioned seems to target the psychological state of being in a state of moral certainty. This feels at least analogous, maybe more, to the epistemological notion of belief or commitment. Some epistemologists, like Jennifer Nagel and Brian Weatherson, have emphasized that whether one is in this state depends (causally or constitutively, respectively) on the practical situation—when the stakes are high, one is less likely to believe. Maybe moral certainty is something like, being such that one would count as believing even in very high stakes cases. And although this state isn't, as Woods points out, sufficient for appropriate conviction, a normative connection seems plausible: one should only be in this state if one has a proof of corresponding strength. Don't be sure unless it's proven.

It's hard for me not to think in terms of knowledge. One contextualist way of mapping these thoughts would have it that, given a high standard for knowledge, all and only that which is proven beyond a reasonable doubt is 'known', and jurors should vote to convict if and only if they know the defendant guilty. I think this could make sense of these issues—although it'll probably be too simple in other respects, such as the restriction of admissible evidence. (Some things jurors know, they're not supposed to consider. (Or maybe a weird standard could count them as unknown? Something to think about.))

Anyway, I know I'm being really naive here, but I'd be interested in digging in a little bit, if anyone has ideas or reading suggestions.