Thanks. The first two tiers wouldn't seem to owe much to conventional notions about "judicial economy."It's misleading to refer to the original court as the "trial court". In the Italian system, (what Americans, etc. would think of as) the "trial" consists of a three-stage process of which the current proceedings are the second stage. (A defendant is not "convicted" until all three stages are complete.) That's why Italians refer to this as the "appeal trial". At this (second) level, the entire case -- exhibits, testimony, etc. as well as legal rulings and logical inferences from the facts -- can be reviewed. The "standard of review", if you like, is de novo; "the verdict was against the weight of the evidence" is apparently a legitimate ground for appeal in Italy. (Incidentally, a common misconception is that the current court in this case decided to review only the DNA evidence; however, what last month's hearing decided was that they were going to seek expert consultation on the DNA evidence. They can still review the rest of the case themselves, and as far as I know, will.)
At the third level (the "cassation" level), only legal issues (and possibly factual inferences, I'm not clear on this) are reviewed, and hence this stage is closer to what those in English-speaking countries think of as an "appeal" -- although it's still automatic; every defendant gets a hearing, and again, isn't "convicted" until it's done. Some commentators (not usually Italian lawyers) have expressed the opinion that AK/RS have a better chance at the third level than the second, because the third level takes place in Rome as opposed to "provincial" Perugia. This has always puzzled me, because -- though lawyers are skilled in cleverly manufacturing legal issues out of factual ones --the important errors in this case are factual, not legal, and so it would seem that the second level would be the appropriate place to expect them to be addressed if they're going to be addressed at all. I suppose it depends on whether the third-level court can indeed review the factual inferences of the lower courts in addition to the legal rulings (i.e. look at the motivation and say "that reasoning about the knife being the weapon is terrible" in addition to "the decision to deny that request was incorrect according to Italian law").
Should you find yourself with nothing better to do, perhaps you might expound on the relative functions of judges and jurors in the appeals court.