The law requires immediate benching of any student who has or may have suffered a concussion in a school-related activity, including sports and gym classes.
Students can play again only after they are symptom-free for 24 hours and cleared by a doctor.
Concussions are usually temporary, but can cause headaches and problems with concentration, memory, judgment, balance and coordination.
Sponsors say athletes need to be protected from further injury and possible long-term effects.