The law of advantage takes precedence over most other laws and its purpose is to make play more continuous with fewer stoppages for infringements. Players are encouraged to play to the whistle despite infringements by their opponents. When the result of an infringement by one team is that their opposing team may gain an advantage, the referee does not whistle immediately for the infringement. The referee is sole judge of whether or not a team has gained an advantage. The referee has wide discretion when making decisions.
Tactical advantage means freedom for the non-offending team to play the ball as they wish.
The advantage must be clear and real. A mere opportunity to gain advantage is not enough. If the non-offending team does not gain an advantage, the referee blows the whistle and brings play back to the place of infringement. Advantage must not be applied when the ball, or a player carrying it, touches the referee. Advantage must not be applied when the ball comes out of either end of the tunnel at a scrum without having been played.