Players making contact with an opponent’s head in “reckless tackles” will receive a yellow card at least in changes to rules over high tackles.
Players will be punished even if the tackle starts below the shoulders.
If head contact is accidental – for example, if a ball-carrier slips into a tackle – a penalty will be awarded.
World Rugby says the new rules, which come into effect on 3 January, “aim to change culture in the sport to ensure that the head is a no-go area”.
A player is deemed to have made reckless contact during a tackle or attempted tackle or during other phases of the game if in making contact, the player knew or should have known that there was a risk of making contact with the head of an opponent, but did so anyway. This sanction applies even if the tackle starts below the line of the shoulders. This type of contact also applies to grabbing and rolling/ twisting around the head/ neck area even if the contact starts below the line of the shoulders.
Minimum sanction: Yellow card
Maximum sanction: Red card
When making contact with another player during a tackle or attempted tackle or during other phases of the game, if a player makes accidental contact with an opponent’s head, either directly or where the tackle starts below the line of the shoulders, the player MAY be sanctioned. This includes situations where the ball carrier slips into the tackle.
Minimum sanction: Penalty
For further detail and examples please refer to : http://laws.worldrugby.org/?domain=9&language=EN