Hitting an opponent from behind is a penalty. It carries an automatic minor penalty and misconduct, or a major penalty and game misconduct if it results in injury. See checking. This is generally allowed in the NHL unless it's covered by another penalty such as boarding or illegal check to the head.
|Ice hockey penalties|
|Types of penalties||Minor Penalty - Major Penalty - Misconduct - Game misconduct - Match Penalty - Penalty shot - Gross misconduct - Stacked penalties|
|Infractions||Abuse of officials - Aggressor penalty - Attempt to injure - Boarding - Butt-ending - Charging - Checking from behind - Illegal check to the head - Clipping - Cross-checking - Delay of game - Diving - Elbowing - Fighting - Goaltender Interference - Goaltender Leaving Crease - Head-butting - High-sticking - Holding - Holding the stick - Hooking - Illegal equipment - Illegal substitution - Instigator penalty - Interference - Joining a fight - Kicking - Kneeing - Playing with too many sticks - Roughing - Secondary altercation - Slashing - Slew footing - Spearing - Starting the wrong lineup - Too many men on the ice - Tripping - Unsportsmanlike conduct|