Substitutions, replacements, and HIA rules.

Substitution or replacement?

In everyday speech, people often say "substitution." In the rugby union law book, the usual word is "replacement." The idea is the same at a basic level: one player leaves and another player enters. The important part is the type of change.

A tactical replacement is a coach's choice. A permanent injury replacement is made because a player should not continue. A temporary replacement is allowed only for specific situations, mainly blood injuries and Head Injury Assessment procedures in approved matches. Those labels decide whether the original player can come back.

How many replacements are allowed

World Rugby Law 3 says an international team may nominate up to eight replacements. For other matches, the match organiser sets the number, up to a maximum of eight. Local, community, age-grade, tournament, and modified formats can therefore use different match-day limits.

The team still cannot have more than 15 players in the playing area during play. If a replacement enters without permission and the referee believes the team did so to gain an advantage, the player is guilty of misconduct and the sanction is a penalty.

When a player may enter

A normal replacement is made only when the ball is dead and only with the referee's permission. The replacement must be eligible, the departing player must be managed properly, and the team must not briefly create an extra active player.

• The change should happen at a stoppage, not while the ball is live.
• The referee or appointed match official must allow the change.
• The replacement must come from the nominated replacements unless a law exception applies.
• The team remains responsible for tracking who has been tactically replaced, temporarily replaced, or permanently replaced.

A tactical replacement usually stays off

When a player is tactically replaced, that player is not normally free to return later just because the coach wants to reverse the decision. Rugby union is not an unlimited rolling-substitution sport at the standard law level.

A tactically replaced player may return only in defined exceptions, such as replacing an injured front-row player, a player with a blood injury, a player with a head injury, a player injured by foul play verified by the match officials, the nominated player in certain front-row card situations, or in elite rugby after a qualifying 20-minute red-card replacement process.

Permanent injury replacements

An injured player may be permanently replaced when it is not advisable for that player to continue. At national representative level, that opinion normally comes from a doctor. In other matches, the match organiser's medical arrangements and the referee's judgement can matter.

Once a player is permanently replaced for injury, that player may not return to the match. The point is player welfare: if the player has been removed because continuing is unsafe, the replacement is not a short rest or a tactical reset.

Recognise and remove

If a player is concussed or has suspected concussion at any point, the player must be immediately and permanently removed. That rule is separate from the HIA process. It applies as a safety baseline when concussion is known or suspected.

This is a common source of confusion. An HIA is not a way to keep clearly concussed players available. Where the signs or medical judgement require permanent removal, the player is out of the match.

Temporary blood replacements

A player with a blood injury may leave and be temporarily replaced while the bleeding is controlled or covered. If the player is not available to return within 15 minutes of actual time after leaving the playing area, the temporary replacement becomes permanent.

In international matches, the match-day doctor decides whether the injury is a blood injury requiring a temporary replacement. In matches approved for HIA, play cannot restart until the player with the blood injury has been temporarily replaced.

How HIA temporary replacement works

The Head Injury Assessment process applies only in matches approved in advance by World Rugby for HIA. In those matches, a player who requires an HIA leaves the field and is temporarily replaced, even if the team has already used all its replacements. The game cannot restart until that temporary replacement has happened.

If the player is not available to return after 12 minutes of actual time from leaving the playing area, the replacement becomes permanent. If the player also has a blood injury, up to five minutes may be used to stem the bleeding before the 12-minute HIA period begins.

Why front-row changes are different

Props and hookers have extra replacement rules because contested scrums require suitably trained and experienced front-row players. Teams must identify front-row players and their possible replacement positions before the match.

If a front-row player leaves through injury, a yellow card, or a red card, the referee checks at the next scrum whether the team can continue with contested scrums. If not, uncontested scrums may be ordered. In some card situations, another player may have to leave temporarily so an available front-row replacement can come on and keep the scrum safe.

A card is not a normal substitution

A yellow-carded player is temporarily suspended. The team plays short during the suspension and cannot simply send on a substitute to avoid the sanction. A red-carded player is removed from the match and cannot return.

Elite rugby has a 20-minute red-card replacement law-trial process for qualifying red cards. That does not mean the sent-off player returns. It means an available replacement may be allowed after 20 minutes of playing time. Permanent red cards still exist for actions treated as highly dangerous and intentional under the active protocol.

When local rules vary

World Rugby law allows a match organiser to implement rolling tactical replacements at defined levels of the game, with no more than 12 interchanges. The organiser is responsible for the administration and rules for those rolling replacements.

That is why a school, amateur, tournament, or development match may not look exactly like a Test match. The safest practical reading is to separate the standard law from the competition's own regulations before assuming a player can return.

What fans often miss

• "Eight replacements means eight substitutions in every match": not always. International teams may nominate up to eight; other match organisers set their own number up to that maximum.
• "A replaced player can always come back": no. Tactical return is limited to specific exceptions.
• "HIA is available in every game": no. HIA temporary replacement applies only in matches approved for that process.
• "A blood replacement stops the match clock": no. The 15-minute blood period is actual time, not playing time.
• "A yellow card can be covered by the bench": no. The team plays short, apart from technical front-row adjustments needed to keep scrums safe.

How officials manage it

1. Confirm the ball is dead unless a specific medical or safety process requires immediate action.
2. Check that the replacement is eligible and that the team will not exceed 15 players.
3. Identify the type of change: tactical, permanent injury, blood, HIA, front-row, or card-related.
4. Record whether the player who left may return and under what exception.
5. Restart only when the replacement process is complete and the referee is satisfied play can continue safely.
6. Penalise illegal entries or extra-player advantage where the law requires it.

Source material

• World Rugby Law 3: Team
• World Rugby Laws of the Game
• World Rugby: 20-minute red-card replacement guideline
• World Rugby Law 19: Scrum