US Soldiers Pose With Dead Civilian Corpses

Of course he's legally responsible but you have to understand no US President in the frigging world could've prevented that.

I'm not so sure about that. If we didnt jump into a couple illegal wars, then we probably wouldnt have foreigners to torture. Step 1 to prevention would be to limit war (something Bush and Obama have made no attempt to do). Step 2, would obviously be to consistantly order your Generals and higher level officials to not accept torture and inhumane acts (something Bush did the opposite of, he ordered torture) and order them to constantly remind all lower level officials.
Next, it would be important to properly screen all applicants. If you find that an applicant is unfit and immoral, then dont accept them into the Armed Forces.

Of course, these are just a few small things, and also I should mention that the entire responsibility is not only put on Obama. The responsibility is on all commanding officiers. The fact that these events occur means that there is a clear flaw in the system.