All the complaints essentially allege that the NFL ignored studies and other evidence linking brain damage and football that date to the late 19th and early 20th centuries. One evokes the great coach Pop Warner, who in 1913 noted he had “many times seen cases where hard bumps on the head so dazed the player receiving them that he lost his memory for a time and had to be removed from the game.”
The players say the league even disputed its own studies. In 2007, retired Chicago Bears safety Dave Duerson cast doubt on a link to brain damage in testimony before a congressional committee with comparisons to his father, who had Alzheimer’s disease but never played a professional sport.