A concussion substitute is a player who replaces another player who is out with a concussion or suspected concussion during an international cricket match). The rule came into effect on August 1, 2019, and allows teams to replace a player who has sustained a head or neck injury during an international match and has subsequently been diagnosed with concussion or suspected concussion. The substitute can bat and bowl in place of the injured player, and match officials have to determine that the new player is a "like-for-like" replacement). The ICC Match Referee should ordinarily approve a Concussion Replacement Request if the replacement is a like-for-like player whose inclusion will not excessively advantage his team. The rule was introduced to ensure player safety and to prevent players from continuing to play following a concussion, which can have serious long-term health consequences). The concussion substitute rule has been used in international cricket matches since its introduction, and there have been several instances where players have been replaced under this law.