Finding the truth is also the aim of the American judicial system (it would be ridiculous if it weren't). It's just not always the aim of the defending and prosecuting lawyers (though it may be the goal for one of them or even both, depending on the situation and their knowledge about it).1) The fact that the defendant's lawyer has to disprove may mean (to my eyes) that the lawyer has to gather proves of its own that disproves the prosecutor's proves. If you can be proven guilty, then you may want to be proven innocent to avoid any new prove: i wasn't there at the time of the crime.
In France, this work of proof gathering is supposely done independantly and the goal is not to prove someone is guilty or innocent but to find the truth. On a philosophical level, it's totally different.
However, again, that the defendant is innocent does not need to be proven. There's a difference between explaining away or disproving the prosecutor's evidence and proving innocence.
Well I'm sorry if I sounded rude, but you didn't address the point I was making when I said you were wrong the first time, so I had to presume you deliberately ignored it. I also saw no reason to repeat what I wrote above because, well, you didn't address it the first time.2) may i make a remark on the form of your post? saying "that's false. see above" is rude to my eyes. I have read your previous statement and I think i made my point with previous examples. You may disagree with me, and i would accept it. Your post deny all attemps to discussion.