Massachusetts passed a "concussion law" last year. All the responsibility is with schools and parents; officials are not mentioned at all.
The state law...and corresponding direction from the MIAA, however...calls for stronger action than the NFHS rules. If a player is sent out of a game (or practice) with symptoms of a concussion, he may not return that day at all...and may not return without written permission from a health-care professional to the school athletic director.
Details here:
Concussion Update Issues