In practice, in the United States, over 90% of criminal cases are determined in favour of the government without trial, because the prosecutors press-gang witnesses by threatening them with prosecution themselves, granting immunities for prosecution for perjury and frog-marching them into court in great numbers.
Unfortunately, this is the essence of it.
Given that, the outcome in the case out of Perugia, Italy is more than a little interesting as a comparative matter, as Black notes. Whatever its other flaws, the Italian system has shown itself to be far more amenable to self-correction than the US system.
The argument that “correction” should be made difficult rests on the proposition that there’s no better chance you’re going to get it right the second time around than the first. There is merit to this. Were they right in Italy the first time, or the second? I don’t really know, though I strongly suspect the latter. The tale of “Amanda Knox killed Meredith Kercher” was preposterously lurid; believing it would require a mountain of evidence with little or nothing to contradict it.
What we sometimes have to come to terms with is that juries get it wrong. It may be difficult to say just when this happens, but the American approach has an impervious and largely dishonest rigidity: sure, there is a “presumption of innocence” that may not be applied elsewhere, but then it isn’t really applied here either. It is almost completely illusory. Nobody really believes in it.
On the other hand, the presumption in favor of a jury verdict of “guilty” in a criminal case when on appeal or in post conviction proceedings could be ranked with death and taxes in terms of certitude. Appellate courts never second guess jury verdicts per se or explicitly; they must have some extraneous excuse to disturb one. They almost never find such an excuse. They almost never want to.
That there is no meaningful review of cases on appeal in the United States is quietly conceded by appellate judges themselves.
We could learn something from Italy, I think. But I don’t think we will.