Players must not do anything that is reckless or dangerous to others.
A player must not physically or verbally abuse anyone. Physical abuse includes, but is not limited to, biting, punching, contact with the eye or eye area, striking with any part of the arm (including stiff-arm tackles), shoulder, head or knee(s), stamping, trampling, tripping or kicking.
A player must not tackle an opponent early, late or dangerously. Dangerous tackling includes, but is not limited to, tackling or attempting to tackle an opponent above the line of the shoulders even if the tackle starts below the line of the shoulders.
A player must not tackle an opponent who is not in possession of the ball.
Except in a scrum, ruck or maul, a player who is not in possession of the ball must not hold, push, charge or obstruct an opponent not in possession of the ball.
A player must not charge or knock down an opponent carrying the ball without attempting to grasp that player.
A player must not tackle, charge, pull, push or grasp an opponent whose feet are off the ground.
A player must not lift an opponent off the ground and drop or drive that player so that their head and/or upper body make contact with the ground.
Dangerous play in a scrum.
The front row of a scrum must not form at a distance from its opponents and rush against them.
A front-row player must not pull an opponent.
A front-row player must not intentionally lift an opponent off their feet or force the opponent upwards out of the scrum.
A front-row player must not intentionally collapse a scrum.
Dangerous play in a ruck or maul.
A player must not charge into a ruck or maul. Charging includes any contact made without binding onto another player in the ruck or maul.
A player must not make contact with an opponent above the line of the shoulders.
A player must not intentionally collapse a ruck or a maul.
A player must not retaliate.
Teams must not use the ‘cavalry charge’ or ‘flying wedge’.
A player must not attempt to kick the ball from the hands of the ball-carrier.
A ball-carrier is permitted to hand off an opponent provided excessive force is not used.
A player must not intentionally charge or obstruct an opponent who has just kicked the ball.
Source World Rugby Laws