The line was not so fine in this case. The problem was that they had some really stupid jurors (you only had to listen to some of the interviews to verify that), and one or two who I think wanted to have the verdict that would sell best for a book or movie. (Didn’t work out so great, tough luck.) For our jury system to work correctly, we need both intelligent (not just book learning, but the ability to reason as well) and ethical people to sit on them. A reasonable jury would have found this woman guilty.
Ignorant jurors aside, I do not believe the prosecution proved their case. Too much junk science along with a failure to adapt to the tactics used by Baez. Also, so much of what could have clinched the deal never made it into court because it was hearsay. The big family blowup the night before is a perfect example.