When must I order uncontested scrums?

Under World Rugby Law 3 (2026):

• Scrums become uncontested if either team can't field a suitably trained front row, or if the referee orders it.
• Each team must tell you before the match which players (starters and replacements) can play front row, and in which positions. Only those players may play front row in a contested scrum, and only in their nominated positions.
• It's each team's responsibility to make sure its front-row players and replacements are suitably trained and experienced.
• When a front-row player leaves the field (injury, yellow card or red card), ask at the next scrum whether the team can continue with contested scrums. If they say they can't, order uncontested scrums. If the player returns or another front-rower comes on, contested scrums can resume.
• Uncontested scrums caused by a sending off, yellow card or injury must still be played with 8 players a side.
• Another player may only play in the front row when no replacement front-row player is available.
• A match organiser can set conditions for a game to start with uncontested scrums, and can decide that a player whose departure caused uncontested scrums can't be replaced.

In an uncontested scrum, the team throwing in wins the ball: there's no pushing and no contest for possession.