When can I report foul play to the referee?

Under World Rugby Laws 2026 (Law 6):

• The match organiser may give assistant referees the authority to signal foul play. Check that you have it before the match.
• To signal that foul play or misconduct has been seen, hold the flag horizontally and point infield at right angles to the touchline.
• After signalling, stay in touch and carry on with all your other duties until the next stoppage in play.
• At the referee's invitation you may then enter the playing area to report the offence. You may do this only at the next stoppage in play and when the referee allows. The referee then takes appropriate action.
• If your verbal report leads to a player being sent off, you submit a written report to the referee as soon as possible after the match.

Source: World Rugby Laws of the Game 2026, Law 6 and the assistant referee signals page: https://passport.world.rugby/media/wnvjlxtb/2607en-world-rugby-laws-final-compressed.pdf