Obstruction is the line between a decoy and a block.

What obstruction means in sevens

Obstruction is foul play when a player prevents an opponent from making a fair play on the ball, the ball-carrier, or the space needed to compete. Common words for it are blocking, screening, crossing, taking out a defender, or running interference.

The rule applies to attackers and defenders. An attacking support runner can obstruct a tackler. A defender can obstruct a chaser or support player. An offside player can obstruct simply by using an illegal position to interfere with play.

Why small blocks matter more

Sevens is played on a full-size rugby field with only seven players per team. That means every defender covers more space, and losing one defender to an illegal screen can create a clear break immediately.

Referees therefore focus on material effect. Contact that looks minor on replay may still matter if it stops a defender sliding, tracking inside, or attempting a tackle. Contact away from the ball may be ignored if it did not affect any realistic play.

What players are allowed to do

Not every collision or crossed running line is illegal. Rugby allows players to run support lines, hold legal positions, compete shoulder-to-shoulder when both are running for the ball, and use decoy runners to ask defenders to make decisions.

• A decoy runner may run hard at a defensive line if they do not deliberately block a defender from tackling the ball-carrier.
• A support player may be near the ball-carrier if they stay onside and do not use their body as a screen.
• A player may contest possession, chase a kick, or run for loose ball from a legal position.
• Players in rucks, mauls, scrums, and lineouts may make contact that belongs to that contest, provided they enter and bind legally.

When a decoy becomes a block

A legal decoy becomes obstruction when the runner's line, contact, or position prevents a defender from making a tackle or playing the ball. The referee asks whether the defender was entitled to make that play and whether the attacking player took that option away illegally.

• A decoy runner who runs into a defender and opens a gap for the ball-carrier is at risk of a penalty.
• A support runner who stands in front of the ball-carrier and shields the tackle line can be penalised.
• A ball-carrier who runs behind a team-mate and uses that team-mate as a barrier can be called for crossing.
• A player who blocks a defender after passing the ball can still obstruct if the defender was trying to tackle or chase legally.

Crossing is about the defender's path

Crossing usually means two attacking players overlap their running lines. It is not automatically illegal. It becomes illegal when the movement causes a team-mate to act as a shield between a defender and the ball-carrier.

For example, a switch pass is legal if the receiver takes the ball and the old runner does not block defenders. If the old runner runs into the defensive line and prevents a defender from reaching the new ball-carrier, the referee may call obstruction even if the pass itself was legal.

Offside obstruction is separate but related

World Rugby's open-play offside law says an offside player must not interfere with play. One way to interfere is by preventing opponents from playing as they wish, which often overlaps with obstruction.

In sevens, this can happen when a player ahead of the kicker blocks a receiver's support line, when a retreating player gets in the scrum-half's passing lane, or when a player in front of the ball shields a defender. The referee may describe the call as offside, obstruction, or both, but the practical result is usually a penalty.

Blocking on kicks and loose balls

Players running for a kicked or loose ball may compete for position, but they cannot charge, push, hold, or block an opponent unless the contact is part of a fair shoulder-to-shoulder contest for the ball.

A chaser who changes line to take out a receiver's protector, or a retreating player who deliberately blocks an onside chaser, risks an obstruction penalty. If a player is offside from the kick and then blocks or interferes, that makes the infringement clearer.

Contact phases do not excuse blocking

Rucks and mauls involve legal contact, but players still have to enter from legal positions and stay within the rules of that phase. A player who joins through the side, swims around the edge, or stands ahead of the ball to screen defenders can be penalised.

Mauls are the most common place for confusion. A bound, onside player can be part of a legal drive. A detached player moving ahead of the ball-carrier to block defenders is no longer just part of the maul; the referee can treat that as obstruction or offside.

Restarts can create quick obstruction calls

Sevens restarts happen often because the scoring team kicks off after scoring. Team-mates must be legally positioned at the kick, and chasers must compete without blocking receivers or support players.

A player who is in front of the restart kick may already have an offside problem. If that player then screens a receiver, impedes a support runner, or creates contact that stops the receiving team from playing the ball, the referee has a strong basis for stopping play.

What officials usually award

The normal sanction for obstruction is a penalty to the non-offending team. Referees may apply advantage if the non-offending team still gains a useful tactical or territorial benefit.

If obstruction is deliberate, cynical, repeated, or prevents a probable try, officials can consider stronger outcomes such as a yellow card or penalty try. Those decisions depend on the exact sequence, the defender's realistic chance, and whether the illegal action changed the scoring opportunity.

Where people get caught

• "Every decoy runner is illegal": no. Decoys are legal unless they materially block or take out a defender.
• "There must be heavy contact": no. A screen, hold, or lane change can be enough if it prevents a realistic play.
• "The defender would not definitely have tackled him": certainty is not required. Officials judge whether the defender had a realistic opportunity.
• "Standing still cannot be obstruction": it can be, especially if the player is offside or deliberately holds a blocking position.
• "Only the attacking team can obstruct": defenders can obstruct chasers, support players, or opponents trying to play loose ball.

How to read the call

1. Find the ball-carrier, passer, kicker, or loose ball that the opponent was trying to play.
2. Identify the possible blocker and check whether that player was onside and legally positioned.
3. Ask whether the opponent had a realistic chance to tackle, chase, support, or play the ball.
4. Check whether the possible blocker changed line, held position, initiated contact, or used a team-mate as a screen.
5. Decide whether the action materially affected the play: play on, advantage, penalty, or stronger sanction for cynical or try-preventing obstruction.

What this page covers

This explainer covers rugby sevens under the World Rugby law structure. Tournament regulations and referee guidance can affect review process, communication, and sanction emphasis, but the underlying principle is stable: players may create options and compete for space, not intentionally block opponents from a fair play on the ball.

Source material

• World Rugby Law 9: Foul play
• World Rugby Law 10: Offside and onside in open play
• World Rugby Law 12: Kick-off and restart kicks
• World Rugby Law 15: Ruck
• World Rugby Law 16: Maul
• World Rugby Sevens variations