FILE - This Aug. 18, 2009, file photo shows Dr. Stanley Herring, team doctor for the Seattle Seahawks and Mariners, medical director of spine care at University of Washington Medicine and co-medical director of the Seattle Sports Concussion Program, at Seahawks practice in Renton, Wash.  Herring is among the leading proponents of a law requiring a doctor's approval for youth athletes suspected of having a concussion to return to play. It's known as the Zackery Lystedt Law, named for one of his patients _ a then-13-year-old boy who returned to a football game only minutes after a concussion and wound up with a brain injury that's confined him to a wheelchair.(AP Photo/Elaine Thompson, File)

Photo by: Elaine Thompson

FILE - This Aug. 18, 2009, file photo shows Dr. Stanley Herring, team doctor for the Seattle Seahawks and Mariners, medical director of spine care at University of Washington Medicine and co-medical director of the Seattle Sports Concussion Program, at Seahawks practice in Renton, Wash. Herring is among the leading proponents of a law requiring a doctor's approval for youth athletes suspected of having a concussion to return to play. It's known as the Zackery Lystedt Law, named for one of his patients _ a then-13-year-old boy who returned to a football game only minutes after a concussion and wound up with a brain injury that's confined him to a wheelchair.(AP Photo/Elaine Thompson, File)