This is a good overview of the lawsuits involving the NFL and a group of 4,200 former players on the damaging effects of head trauma. The plaintiffs, who are former players, allege that the NFL neglected to publicize and inform them of just how damaging concussive brain injuries are. The NFL is arguing that the issue is covered by the collective bargaining agreement, which would likely prevent the players from bringing suit. It will be interesting how this one turns out, because it will help determine the limits of what constitutes a "collectively bargained agreement."
Regardless of what happens at the district court-level, this is likely to be appealed.