As Lee Corso would say --

Let's correct the record before we let this one go. Lee didn't lead any of the failed charges on July 28th himself, and Hood had no idea what had happened on Lickskillet Road until the first reports came in. He had been directed to defend the position and not attack unless favorable circumstances dictated otherwise. As stated earlier, Lee absolutely ignored Hood's orders at Lickskillet Road and sent his troops to be slaughtered in several unplanned, uncoordinated and ill-considered attacks.

In a strictly technical sense, a superior officer is always responsible for the actions of troops under his command. In an extreme example of this rule, General Westmoreland was ultimately responsible for the actions of Lieutenant Calley in Viet Nam. Hood therefore was responsible as commander of the Army of Tennessee. Here's a great article on that topic which opens with Lee taking responsibility for defeat at Gettsyburg. Of course you'll have to copy and paste the entire URL in your address line to read it --
http://lawofwar.org/Decision%20Making.htm