But clearly, I view the subject of the assertion a bit differently...
Procedural mistakes should not overturn convictions that are this overwhelming.
So, what standard do you propose? Is it OK for the prosecution to withhold evidence because the other guy is "really bad" and it would be a shame if he were acquitted?
I could've sworn we had juries for some reason...
The prosecution in this case withheld evidence from a defendant. They could be - and, if I had to bet money, probably will be - disbarred for this.
Why? Because this little thing called the Sixth Amendment to the Constitution of the United States (the "one book" I imagine you alluding to) grants defendants the right to confront their accusers. That's pretty damn hard to do when the prosecution does not hand over its evidence as it is required to do by law and as the attorneys are required to do by their ethical obligation.
Now, why would this be important? Oh, I don't know. Let's say you get accused of a murder you didn't commit. Sadly, you have no alibi for the night in question and an awful lot of circumstantial evidence just happens to point your way. But, in the course of its investigation, the prosecution happens to turn up a piece of evidence that demonstrates you could not have possibly committed the crime (say you happen to have randomly been caught on a security camera somewhere, whatever, it doesn't really matter what the evidence is). Now, what should the prosecution do? Drop the case. Immediately. But Mr. Prosecutor has an awful lot riding on this case, you know. A promotion. Some political concern. He doesn't want to just walk away from it - he's invested too much, and maybe he thinks you're just a bad guy and should go to jail anyways. So he goes forward with it, and just conveniently "forgets" to hand over that one piece of exculpatory evidence you so desperately needed. You get convicted. Sorry! You're in jail!
Failure to hand over evidence is not merely a "procedural mistake". In this case, it was the result a conscious effort by the prosecution to keep evidence out of the hands of the defense. This is no mistake - this is keeping important information out of the hands of the finder of fact (the jury) so the prosecutors can put someone in jail. This is very, very, very bad. It games the system, it runs the risk of imprisoning the innocent, and it simply should not be allowed.
Now here, to be quite frank, we have a case of a scumbag getting out because the attorneys trying him were also scumbags. But I'd rather this scumbag got off than allow this sort of misconduct to continue. Someday I might find myself as a defendant, and the possibility that the prosecution, which has access to far more investigatory resources than I ever would, could withhold evidence from my attorney that could be used in my defense. There's a reason for the confrontation clause and the proper cross-examination of a witness is simply impossible without full access to evidence.
The practice of law used to require one book, when we found this nation maybe a 100 now there are 10's of thousands of books involving the law in various aspects and it has gotten to be too much.
When, pray tell, did the practice of law - an actual system of laws, not simply a dictatorship - ever require just "one book" in the last thousand years? Hell, look at Roman law, Rabbinical scripts, you name it. Are you thinking about Hammurabi's Code or something?
As to "maybe 100" books when this nation was "found" [sic]? Please. American law is based on English Common Law, which by 1776 was quite voluminous and filled libraries. There was far more to it than a mere "100 books".
As to the "10's of thousands of books" dealing with the law now, it's true. There are lots of books dealing with the law, including uncountable volumes of case law. That's just how it works in a common law system - each year, people seem to piss other people off and do each other wrong, so they keep going to judges who keep ruling on things.
But forget about the quantity of books for a moment. Your argument isn't truly based on quantity, but supposedly on complexity. This makes your argument only more wrong.
The legal requirement that prosecutors hand over evidence of this sort is one of the most basic things they teach you in law school. It's obvious. It's common sense. It's required by the Constitution. That any attorney would screw it up shows that that attorney is either a) too saliva-dribbling-from-his-gapping-mouth-dumb or negligent to practice law or b) that the prosecuting attorney is purposefully hiding the evidence from the other side. Either act - even negligence of this magnitude - could well end a lawyer's career for breach of ethics. Remember the prosecutor in the Duke case, for example? There is a reason that the judge lectured the prosecutors in this case by reading from a first-year law school book. When a judge does that to you, you cannot possibly doubt that you have not only screwed up, but completely, irrevocably, embarrassingly screwed up.
This isn't a minor screw up. This isn't a mere "procedural" issue. This isn't some obscure regulation. The prosecutors on this one completely missed their obligations and might have done so with malicious intent. That a scumbag gets off because they did this is unfortunate, but it is also required in order to maintain an honest system of justice.