The nfl is going to lose this case and they know it. Look at the facts and it's obvious. Playing in the nfl causes damage to the body and brain. That is accepted as fact. By employing team doctors that hand out medication so that players can play thereby ignoring injuries or medicating to get through with known potential harm going to happen is an open and shut case. The nfl knows this.
As far as personal responsibility there is going to be the arguement made that they will lose their job if they do not keep playing with an injury or be pressured by the setting to continue to play for the good of the team.