These players are protected by rules that have been in place for many years. It
is of the utmost importance that participants, coaches and game officials carefully
and diligently observe safety rules.
Intentional helmet-to-helmet contact is never legal, nor is any other blow
directed toward an opponent’s head. Flagrant offenders shall be disqualified.
http://www.eaifo2.org/files_pdf/2009_football_rules.pdf