Concussion Substitute Rule in Cricket: Full Guide

Cricket is a sport played with a hard ball that can travel at over 90 miles per hour. In that context, it is surprising — in retrospect — that it took until 2019 for cricket to introduce a rule specifically designed to protect players who sustain a head injury during a match. The concussion substitute rule is now an established part of ICC playing conditions, but its implementation has been surrounded by controversy almost from the beginning. This complete guide explains every aspect of how the rule works, who approves substitutions, what "like-for-like" actually means, and why the rule remains contested.

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What is a Concussion Substitute?

A concussion substitute is a replacement player who can be brought into a cricket match in place of a player who has been diagnosed with a concussion during the match. Unlike other forms of substitute in cricket (the general substitute fielder, which is available only for fielding and not batting or bowling), a concussion substitute is a full replacement — they can bat, bowl, field, and keep wicket in place of the injured player.

The concussion substitute rule was introduced to bring cricket into alignment with the concussion management practices of other major sports, where player safety regulations require that anyone showing symptoms of concussion be removed from play immediately. Before the rule existed, a player who was struck on the head and showed concussion symptoms faced a difficult dilemma: leave the field and leave their team short, or continue playing at risk to their health.

The rule removes that dilemma. If a player sustains a concussion during a match, they can be replaced without their team being penalised by playing with ten players for the remainder of the match.

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When Was the Rule Introduced?

The ICC introduced the concussion substitute rule for international cricket in August 2019, ahead of the 2019-20 Australian summer season. The timing was partly influenced by growing awareness of the long-term risks of concussion in professional sport — driven by high-profile cases in cricket itself, including Phil Hughes's tragic death in November 2014 (though that was from a vertebral artery dissection rather than concussion, it raised acute awareness of head-injury risks in the game).

The rule was formally adopted by the ICC and incorporated into ICC Playing Conditions for all international Test matches, ODIs, and T20 Internationals from August 2019 onwards. It has subsequently been adopted by many domestic cricket boards for their major competitions, including the IPL.

The first notable use of the concussion substitute in international cricket occurred in the 2019 Ashes series, during the second Test at Lord's, when Australia's Steve Smith — already playing an extraordinary series — was struck on the neck by a Jofra Archer bouncer and showed symptoms of concussion. Smith was withdrawn and Marnus Labuschagne entered as the concussion substitute. Labuschagne performed well in the match, sparking immediate debate about the like-for-like criterion.

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What is the Process for Approval?

The concussion substitute process involves several steps and requires approval from the ICC Match Referee (or the relevant match referee for domestic tournaments). It is not a decision that the team captain or team doctor can make unilaterally.

Step 1 — Player sustains a potential concussion: If a player is struck on the head or neck, or shows any symptoms of concussion during play, they must be assessed by the team doctor. The team has an immediate responsibility to remove the player from the field for a Head Injury Assessment (HIA).

Step 2 — Medical assessment: The team's doctor conducts a concussion assessment using a standardised protocol. If the player is confirmed to have a concussion or cannot pass the concussion assessment, they are deemed unfit to continue playing.

Step 3 — Application to the Match Referee: The team captain and/or team manager applies to the match referee for permission to use a concussion substitute. The application must be made promptly — the team cannot simply wait and see how the player feels. The application includes the medical report and a nomination of the proposed replacement player.

Step 4 — Match Referee decision: The match referee reviews the medical information and assesses whether the proposed replacement meets the like-for-like criteria (explained next). The referee can approve the substitute as proposed, suggest an alternative player who better meets the criteria, or, in theory, refuse the application if the medical grounds are not established. In practice, if a proper medical concussion diagnosis has been made, the match referee approves the substitute.

Step 5 — Substitute enters: Once approved, the concussion substitute enters the match in place of the injured player. The injured player may not return to the match even if their symptoms resolve — once replaced, the substitution is permanent for that match.

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What Like-for-Like Actually Means

The "like-for-like" criterion is the most debated and practically consequential aspect of the concussion substitute rule. The ICC's playing conditions state that the replacement player must be "the most appropriate replacement for the concussed player" — in practice, this means the substitute should perform a similar role in the team to the player they are replacing.

In practice, like-for-like means:

• If the injured player is a specialist batsman, the substitute should be a batsman of similar batting order position and style (not a specialist fast bowler)
• If the injured player is a specialist bowler, the substitute should bowl a similar type (pace for pace, spin for spin)
• If the injured player is an all-rounder, the substitute should be an all-rounder or similarly versatile player
• The substitute comes from the named squad for that match — you cannot bring in a player from outside the squad

What like-for-like does NOT mean:

• The substitute does not need to be of identical ability — cricket has no provision for ranking or comparing player quality
• The match referee does not reject a substitute because the replacement is "better" than the injured player — there is no objective measure for this
• The substitute does not need to bat in exactly the same position in the batting order as the concussed player (though teams typically maintain continuity)

The Labuschagne-for-Smith case in the 2019 Ashes became controversial precisely because Labuschagne went on to score heavily after replacing Smith, leading critics to suggest that the substitute had exceeded the "like-for-like" spirit by outperforming the player he replaced. But this criticism misunderstands the rule — the standard is about role, not performance, and no rule can legislate for a replacement player performing better than expected.

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Can a Concussion Sub Bat and Bowl?

Yes — and this is the critical distinction between a concussion substitute and a general substitute fielder.

A general substitute fielder (used when a player is temporarily off the field for any reason — injury, illness, or other cause during a match) can only field. They cannot bat, bowl, or keep wicket. This has always been the case in cricket.

A concussion substitute is a full replacement and can perform all of the following:

• Bat — in any position in the batting order
• Bowl — including in overs already allocated to them by the captain
• Field — in any position
• Keep wicket — if the concussed player was the designated wicketkeeper

The fact that a concussion sub can bat and bowl is what makes the rule such a significant departure from normal cricket substitution rules, and why the like-for-like criterion matters so much. Without a like-for-like restriction, a team could theoretically seek to "upgrade" a player through a concussion substitute — replacing a mediocre batsman with a better one under the guise of concussion management. The match referee's scrutiny of the substitute nomination is designed to prevent this.

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Who Approves the Concussion Sub?

The ICC Match Referee is the sole authority for approving a concussion substitute in international cricket. This is not delegated to the on-field umpires, the team captain, or even the team doctor — the final decision is the match referee's.

In domestic competitions that have adopted the concussion substitute rule (such as the IPL, the Big Bash League, and county cricket), the approval authority is typically the match referee appointed for that competition or the tournament director, depending on the specific regulations of that competition.

The team doctor's medical assessment is the primary evidence the match referee considers. A concussion diagnosis based on a standardised HIA protocol — the same SCAT (Sport Concussion Assessment Tool) used in rugby, AFL, and other contact sports — is essentially the trigger for approval, provided the like-for-like substitution is appropriate.

The match referee records the concussion substitute decision in the official match report, which is submitted to the ICC (or the relevant governing body) after the match.

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Famous Concussion Substitute Controversies

Marnus Labuschagne for Steve Smith — 2019 Ashes, 2nd Test at Lord's: The first high-profile use of the concussion substitute rule. Steve Smith was struck by a 92 mph Jofra Archer bouncer and diagnosed with concussion. Marnus Labuschagne came in as the replacement — the first concussion substitute in Test history. Labuschagne scored 59 in the second innings and went on to become one of the best batsmen in the world that series, fuelling debate about whether the substitute rule provided Australia with an unfair advantage. The ICC stood by its decision, noting that Labuschagne was the correct like-for-like replacement as a top-order batsman.

Rishabh Pant replacement discussions (2022-23): Following Rishabh Pant's car accident in December 2022, discussions arose about how India would manage without their first-choice wicketkeeper-batsman. While this was not a mid-match concussion sub situation, it highlighted broader questions about player replacement rules and India's squad depth in that role.

IPL concussion substitute disputes: Several IPL seasons have produced concussion substitute applications that were approved by match referees but criticised on social media and in commentary as attempts to gain tactical advantage rather than genuine player safety decisions. The most commonly criticised scenario is when a batting team's lower-order bowler sustains a head impact and the requested concussion sub is a significantly better batting-capable player.

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Criticism of the Rule

Despite its player safety rationale, the concussion substitute rule has attracted sustained criticism from players, commentators, and administrators:

"It is open to abuse": The most common criticism is that teams could potentially time a concussion assessment or exaggerate symptoms to trigger a substitute they want. The match referee approval and standardised medical assessment are designed to prevent this, but critics argue the system relies on medical staff who are employed by the teams being assessed.

"Like-for-like is too vague": Without objective player rating criteria, "like-for-like" is a judgment call. Two match referees might rule differently on the same application. This inconsistency is frustrating for teams and fans who expect consistent rule application.

"It disadvantages teams with shallow squads": Teams with deep squads — particularly India and Australia in their home conditions — have better like-for-like replacement options than smaller cricket nations with narrower squad depth. The rule may therefore give structural advantages to already stronger teams.

"It is rarely available when truly needed": The 5-over or 10-over fielding substitute provisions are more immediately accessible. The concussion substitute process takes time, requires medical assessment, and requires match referee approval — in a fast-moving T20 match, this process may leave a team fielding short while the assessment and approval occur.

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Quick Reference Table

Rule	Detail
Rule introduced	August 2019
Who approves?	ICC Match Referee
Can concussion sub bat?	Yes
Can concussion sub bowl?	Yes
Can concussion sub field?	Yes
Can concussion sub keep wicket?	Yes
General substitute (non-concussion) — can bat?	No
Key criterion	Like-for-like role
Who conducts medical assessment?	Team doctor (using HIA protocol)
Can injured player return?	No — substitution is permanent
First Test concussion sub in history	Labuschagne for Smith, Lord's 2019
Domestic competitions with rule	IPL, Big Bash, County Championship

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Frequently Asked Questions

Can a player fake concussion to get a substitute? This is the central concern critics raise. The safeguard is that the medical assessment must be conducted using the standardised HIA protocol by the team doctor, and the match referee reviews the medical report. Deliberately falsifying a medical report would constitute serious misconduct and could result in significant bans. No case of proven faked concussion has been established in international cricket.

Does the concussion substitute rule apply in all formats? Yes — the ICC's concussion substitute provisions apply in Tests, ODIs, and T20 Internationals. Many domestic competitions have adopted equivalent rules, though specific details may vary by competition.

What if the replacement player is also injured? If a concussion substitute themselves becomes injured during the match, the normal substitution rules apply — a general substitute fielder can replace them for fielding, but no further concussion substitute or full replacement is available. The team may be left short.

Can both teams use a concussion substitute in the same match? Yes. There is no limitation on the number of concussion substitutes per match. If both sides have players who sustain concussions and are diagnosed, both can apply for and receive concussion substitutes (subject to match referee approval and like-for-like criteria in each case).

What is the difference between a concussion sub and a general substitute? A general substitute can field only — they cannot bat, bowl, or keep wicket. They do not require match referee approval. A concussion substitute is a full replacement who can perform all cricket functions, requires medical assessment and match referee approval, and permanently replaces the injured player for the rest of the match.

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The concussion substitute rule reflects cricket's genuine effort to take player safety more seriously in the modern era. Whatever its imperfections — and the like-for-like ambiguity is a real one — the alternative of players continuing to play after a head injury, or teams being penalised for prioritising player health, is clearly worse. As the rule matures and match referees build more case history on like-for-like decisions, its application should become more consistent.

For more in the series, visit /category/cricket-rules.

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Sources:

• ICC Playing Conditions — Concussion Substitute
• ESPNcricinfo — Concussion Substitute Explained
• MCC Laws of Cricket — Law 24 (Substitutes and Runner)