When must scrums be uncontested?

Under Law 3, scrums become uncontested if either team cannot field a suitably trained front row or if you order it. A match organiser may stipulate the conditions under which a game may start with uncontested scrums (under the Game-On variation, uncontested scrums are required from the start of the match if either team has no suitably trained front row or you so order).

• Before the match, each team must tell you its front-row players, possible front-row replacements and the positions each can play. Only those players may play in the front row when the scrum is contested, and only in their designated positions.
• Uncontested scrums caused by a sending off, yellow card or injury must be played with eight players per side.
• When a front-row player leaves the playing area (injury, yellow or red card), you ask at the next scrum whether the team can continue with contested scrums. If not, you order uncontested scrums. If the player returns or another front-row player comes on, contested scrums may resume.
• If a front-row player is yellow carded and the team cannot continue contested, the team nominates another player to leave so an available front-row player can come on. That nominated player cannot return until the suspension ends, or as a replacement.
• Only when no replacement front-row player is available may any other player play in the front row.
• In elite rugby, or at the match organiser's discretion, a player whose departure caused uncontested scrums cannot be replaced.