The Concussion Substitute Rule in Cricket
Since 2019, cricket has allowed a substitute player to replace a concussed player — and the substitute can bat, bowl, and field unlike regular substitutes. This article explains the concussion sub rule, how it works, and when it has been controversially applied.
What the Concussion Substitute Rule Is
The ICC introduced the concussion substitute playing condition in August 2019 — allowing a like-for-like player replacement when a player suffers a concussion during a match: before the rule, a player who suffered concussion had to leave the match and their team played with 10 players — severely disadvantaging the injured team; the concussion sub can bat, bowl, and field like a full member of the team (unlike a standard substitute fielder who can only field and cannot bat or bowl); the replacement must be a 'like-for-like' player — if a specialist batsman is concussed, the concussion sub should be a specialist batsman; if an all-rounder is concussed, the sub should be an all-rounder; and the match referee (not the team) makes the final decision on whether the replacement is appropriate like-for-like.
When a Concussion Sub Can Be Used
The concussion sub can be requested when a player suffers a concussion during the match: the concussion is assessed by the team's medical officer — the player must be assessed as genuinely concussed (not simply 'feeling unwell') to qualify; the process: the team medical officer confirms concussion and notifies the team management, the team management notifies the match officials, the match referee approves the substitution and confirms the like-for-like nature of the replacement; and the concussion sub can come from the team's official squad list — they don't need to be one of the travelling reserves. There is no appeal process for the match referee's 'not like-for-like' decision — the referee's judgment is final.
Controversial Concussion Sub Incidents
The concussion sub rule has produced specific controversies: Steve Smith's concussion sub in the 2019 Ashes (The Oval) — Smith was hit on the head by a Jofra Archer bouncer; England's opponents argued that replacing Smith with Marnus Labuschagne (who then scored 59 valuable runs) was not truly like-for-like; the controversy highlighted a structural issue with the rule — a team that concusses a star player like Smith and replaces with a player of similar quality (Labuschagne) may not be disadvantaged and may in some cases gain an experienced, fresh player for the remainder of the match; and the match referee's like-for-like assessment is inherently subjective — 'equivalent quality' is difficult to define precisely. The rule remains in place with minor refinements to the like-for-like assessment process.
Frequently asked questions
Can a player come back after being a concussion sub?
No — once a concussion sub is in the match, the original player cannot return: the substitution is permanent — the concussed player is out of the match for its entirety and the concussion sub replaces them for all purposes (batting, bowling, fielding) for the remainder of the match; the original player is effectively retired from that match, and the concussion sub's performance counts in the match statistics as the sub's own record (not attributed to the original player); and at the end of the match, the concussion sub's batting and bowling figures appear in the scorecard under their own name — clearly marked as a concussion substitute. This permanent-substitution structure is specifically designed to ensure teams don't use the concussion sub as a tactical rotation (substituting in a fresh player for tactical benefit and then returning the original player).
Does the concussion sub rule apply in all formats?
Yes — the concussion sub rule applies in all international formats where ICC playing conditions are in use: Tests, ODIs, and T20Is all permit the concussion sub under the same conditions; and the rule also applies in ICC events (World Cups, Champions Trophy) under the same like-for-like assessment process. Some domestic competitions have adopted similar rules, though with variations in the assessment process (some domestic leagues use an independent concussion spotter rather than solely relying on the team's medical officer). Club and recreational cricket typically don't apply the concussion sub rule — the rule is specifically designed for elite professional cricket where team squads are large enough to have suitable replacements available.
What counts as a concussion for the purposes of the rule?
The ICC defines concussion for the playing condition as a medical diagnosis from the team's team physician or medical officer based on established sports medicine concussion protocols: the assessment uses standardised concussion tools (the Sport Concussion Assessment Tool — SCAT — is widely used in cricket's concussion protocol); the player must show recognised concussion symptoms (headache, dizziness, confusion, memory impairment, nausea, balance problems); and the assessment must determine that the player should not continue playing on safety grounds. A player who is hit on the head but does not show concussion symptoms (perhaps a blow that was uncomfortable but not concussive) does not qualify for a concussion sub — the team medical officer must confirm genuine concussion rather than simply head contact.