World Rugby is to introduce a trial law change at under-20 competitions that lowers the height of tackle to "below the nipple line" to reduce the risk of head injury.
The current height for a legal tackle is in line with the shoulders. But, after research revealed that 76 per cent of head injuries occurred in the tackle, World Rugby believes the change could reduce risks, particularly of concussion.
The trial aims to change player behaviour through revised on-field and off-field sanctions. It was approved after a study of 1,500 games that concluded that the "risk of injury to both players from a high-contact tackle (when the tackler is upright) is 4.3 times greater than a low-contact tackle".
At the World Rugby Under-20 Championship in France, which begins next week, a high tackle warning will be issued if the tackler does not bend at the waist when tackling and there is clear head contact for either player. Two high-tackle warnings for the same player will trigger a one-match ban.
The trial does not change the law in any way but does introduce post-match sanctioning through the citing process.
Bill Beaumont, World Rugby chairman, said: "I am committed to ensuring that rugby remains at the forefront of injury-prevention, specifically in the area of concussion."