Excerpt from Hockey Canada website:
http://www.hockeycanada.ca/en-ca/Hockey-Programs/Officiating/Standard-of-Play/Directives-on-Standards
Directives on Standards
1. Hooking
The use of the stick on the body of the puck-carrier or the non-puck-carrier to impede the progress or to gain territorial advantage shall be penalized.
The stick placed on the opponent’s body and parallel to the ice surface shall be considered as being in a ‘danger zone’. Once the stick is in this position, any tug or pull of consequence shall be penalized.
Consequence shall be interpreted as:
• any loss of momentum
• causing diminished space between the players
• impeding the opponent’s progress
• causing the opponent to lose balance to any degree
• reducing the opponent’s ability to pass or shoot the puck or to receive a pass
Placing the stick between the opponent’s legs shall be considered as in a ‘danger zone’.
If movement, either lateral or otherwise, is restricted in any fashion, a minor penalty for hooking shall be assessed. Should the opponent be caused to fall by this action, a minor penalty for tripping shall be assessed.
2. Tripping
A player cannot use his stick on the legs or feet of an opponent in a manner that causes the opponent to lose balance and fall.
Hockey is a game of speed and balance in which players frequently go down following incidental contact. Officials must see the foul and not guess in order to make the proper call.
In cases where the official has not seen the infraction but has seen only the end result, officials must be aware that a possible ‘missed infraction’ is justifiable whereas a ‘phantom call’ is unacceptable.
Placing the stick between the legs of the opponent thus causing him to fall should be called tripping. Impeding progress or hindering lateral movement by placing the stick between the legs should be called hooking.
3. Holding
The free hand may be used to push an opponent.
Removing the hand from the stick and placing it on the opponent’s body shall be considered as in a ‘danger zone’. Once the free hand is in this position, any act of consequence shall be penalized.
Consequence shall be interpreted as:
• restraining or impeding progress
• grabbing the body, stick, or sweater
• reducing the opponent’s ability to pass or shoot the puck or to receive a pass
Pin against the boards: The defensive player may make initial contact with the puck-carrier against the boards. Once this initial contact has been made, the defensive player must play the puck. Once the puck leaves the area (on the boards), the onus is on the defensive player to release the opponent immediately.
4. Interference
The non-puck-carrier must be allowed to pursue the puck or to gain his position without being restrained or impeded in any manner.
Finishing the check: An offensive player who is in the process of dumping, shooting, or passing the puck may be hit legally providing the motion of the check was initiated and then completed immediately following the release of the puck. The guideline for the interpretation of this rule is ‘arm-length + stick-length’.
Should the defensive player be within the range of ‘arm-length + stick-length’, he shall be entitled to finish the check legally provided he commits to the check prior to or immediately following the release of the puck.
The puck-carrier should not be excused from an imminent hit simply because he decides to get rid of the puck.
Face-off interference: Players are not permitted to use their stick or free-hand to impede or block the progress of opponents who are in pursuit of the puck or trying to obtain defensive position. These acts shall be penalized as interference. Players are entitled to the ice they occupy and to position themselves between the puck and their opponent.
Battles: Players are allowed to battle for body position using their strength and balance. These battles occur primarily along the boards and in front of the net. Officials must not penalize players for using assets of strength and balance.