A piece of legislation that slipped past us was signed in Alabama earlier in June. As reported (video included) by CBS42 in Alabama;
A new state law signed by Alabama Governor Robert Bentley earlier this month could prevent young athletes from returning to practices or games if they could potentially have a concussion. The athletes will not be eligible to return to their activities until a doctor has ruled that they are fit to play. The law is intended for high school athletes all the way down to pee wee sports, although many college sports already follow the same guidelines.
This brings our total to 21 states with legislation.