Published: Aug 06, 2010 9:22 PM EDT
Updated: Aug 07, 2010 4:30 AM EDT

HOUSTON (AP) — NFL referees will take on more responsibility this season to protect players from helmet-first hits to their heads and necks.

The league has expanded its rules for protecting "defenseless" players from taking shots above their shoulders.

The reworded rules prohibit a player from launching himself and using his helmet to strike a defenseless player in the head or neck. The old rule only applied to receivers getting hit, but now it will apply to everyone.

Also new this season, when a player loses his helmet, the play is immediately whistled dead.

Referee Walt Anderson, who was meeting the Houston Texans on Friday, says the league will monitor how the new rules worked at season's end and then evaluate if they were effective in limiting injuries.