The NFL is adding a clause to the collective bargaining agreement that allows game-day drug testing, but only for performance enhancing substances. The league has finally developed a way to test players on game day that is not "overly disruptive to the clubs." The NFL and the union agreed last week that HGH testing will be part of the new, 10-year collective bargaining agreement.
See "NFL adding drug testing for performance-enhancing substances to game days this season", Chicago Tribune, August 9, 2011