In the case of the law, I believe lawmakers are aware of the apparent contradiction. But the thinking is that the jury is 12 women and men (in most states in the U.S./different in Italy, I know) who are "reasonable people" (the mentally deficient and biased having been excused). And those 12--working together--are the best judges of what is "reasonable."
But I am not exaggerating when I say that on the murder trial where I was a juror, we spent a good half a day on the term, because different levels of murder and manslaughter depend on what are "reasonable" beliefs and what a "reasonable" person would do.
This has probably been brought up here already (I've been busy and unable to follow this thread closely) but I just don't see how reasonable doubt was even debated in this trial when one reads something like this:
[Judge Massei] deliberated with the jurors and was looked to as the expert in the case. They never debated Amanda and Raffaeles guilt or innocence, only whether they should get life (30 years) or a lesser sentence. They felt they were being kind when they gave Amanda 26 years; Raffaele, 25.
http://blog.seattlepi.com/dempsey/2...-bloody-footprints-tested-negative-for-blood/
I guess I have a hard time conceiving of a jury deliberation where there is a "leader" so to speak, who directs the other jurors on the level of punishment to doll out, but not discuss innocence or guilt, since that one person has already made up their mind. This may explain why certain jury members were crying after the verdict was read and why they are quoted as not even being sure of what AK or RS did that night.