MJ aside, how many other performers currently touring have problems with drug and alchohol abuse? A great number I should imagine. If AEG lose this will prove a huge problem for the entertainment industry. Look at the state Amy Winehouse was in towards the end and she kept on doing gigs.
Ultimately I believe that people are responsible for their own health and if they chose to take legal or illegal drugs then concert promoters (however ruthless) should not be held accountable for this.