Rules & the TMO

The knock-on (Law 11)

A knock-on is when the ball goes forward off a player's hand or arm, hits the ground or another player, and isn't immediately caught. The key word is "forward" — relative to the goal line the player is attacking.

What's not a knock-on:

• The ball going off your foot or shin
• An "intentional knock-down" by a defender — that's a separate offence (penalty + likely yellow if blatant)
• You catching your own knock-on before it hits ground or anyone else

Restart: scrum to the non-offending team, at the place of the knock-on (or where the ball was caught after it went forward).

The forward pass (Law 11)

A pass is forward if the ball travels forward relative to the passer — what matters is where the ball ends up vs. where it left the passer's hands. A flat pass is legal. A pass thrown backwards but caught while running fast is legal even if it ends up in front of where it started.

This is the single most-debated call in modern rugby. The TMO uses the trajectory from passer's hands to receiver's hands; the player's running speed is the source of the optical illusion.

The breakdown / ruck (Law 15)

Once one defender and one attacker are on their feet over the tackled player and the ball is on the ground, a ruck is formed. Now:

• Tackler: must release the tackled player and roll away. Going off feet to slow the ball is a penalty.
• Tackled player: must release the ball immediately. Holding on past one play of the ball is a penalty.
• Arriving players: must enter through "the gate" — directly behind their team's hindmost foot. No coming in from the side.
• Hands in the ruck: only legal for a player who arrived first and is on their feet. Once it's a ruck, hands off.

The "jackler" — the defender on his feet over the ball before the ruck forms — is one of the most valuable roles in the modern game.

Offside (Law 10)

The principle: you're offside if you're in front of a teammate who last played the ball, and you can't participate in play until you're put onside (usually by retreating, or your teammate running past you).

The two big practical cases:

• Offside at the breakdown. The "offside line" is the hindmost foot of your last teammate at the ruck. Step over it, you're offside. This is what defensive coaches drill obsessively.
• Offside from a kick. If a teammate kicks ahead, players in front of him at the moment of the kick can't engage with the ball or the receiver until put onside.

The TMO (Television Match Official)

The TMO is a fourth official with replay access. They can intervene in three categories:

1. Try / no-try decisions at any time the on-field referee asks.
2. Foul play — the TMO can flag dangerous tackles, late hits, etc., either when asked or "of their own volition" within strict windows.
3. Last two phases rule — for incidents in the lead-up to a try, the TMO can review the prior 2 phases for missed knock-ons, forward passes, or foul play.

The on-field referee remains the ultimate decision-maker — the TMO recommends, the ref decides. Time wasted in TMO reviews is added to the clock.