The NFL players union filed a grievance on behalf of former 49ers safety Eric Reid, perhaps the most prominent NFL player who protested during the national anthem last season and who remains jobless nearly two months after free agency began.
The NFL Players Association says that an NFL team appears "to have based its decision not to sign a player based on the player's statement that he would challenge the implementation of a club's policy prohibiting demonstration."
The NFL does not have a policy prohibiting players from protesting during the anthem and has said it will respect the players' right to do so.