Concussion substitute cricket rules: how replacements work

A short ball climbs, the batter is late on the pull, and the sound is the one nobody in the ground wants to hear. He stays upright. He takes guard again. Two overs later he plays a shot he would never normally play, the physio walks out, and a conversation begins on the outfield that has nothing to do with the score. What happens next is governed by the concussion substitute cricket rules, a set of clauses that sit in the playing conditions rather than in the Laws and that have been rewritten more than once since they arrived.

The short version is this. If a player suffers a concussion or a suspected concussion during a match, the team may apply to the match referee for a replacement. If the referee approves it, the replacement is a full member of the side: he can bat, bowl, keep and field, and the injured player takes no further part in the game. Approval turns on whether the nominated replacement is a like-for-like swap, judged against the role the injured player would have filled for the remainder of the match. The referee's decision cannot be appealed. Since 2025 sides at international level must nominate candidates for the job before the match starts, one in each of five defined roles, and a player diagnosed with concussion must stand down for a minimum period afterwards.

Almost every dispute the rule has produced comes from the middle sentence of that paragraph. The rest of this piece works through the mechanism a piece at a time.

• 2019Year the protocol entered international cricket
• 5Replacement roles a side must nominate before play
• 7Minimum days a diagnosed player must stand down
• 0Rights of appeal against the referee's decision

Structural features of the ICC playing conditions and the 2025 amendments, not medical guidance.

Where the rule actually lives, and why that matters

The concussion replacement is not in the Laws of Cricket in the way that leg before wicket or the follow-on are. The Laws deal with substitutes in general terms, permitting a side to send a fielder on for an absent player, and that substitute may not bat, bowl or act as captain. That clause has existed in some form for as long as the game has been codified, and it is not a concussion provision.

What governs concussion replacements is a regulation layered above the Laws: the ICC playing conditions for international cricket, and equivalent regulations written by national boards for their own first class and limited overs competitions. That distinction is not pedantry. It explains why the rule differs between competitions, why it can be amended between series without touching the Laws, and why a village fixture on a Saturday afternoon may have no such provision at all unless the league has written one.

The 2022 code of the Laws did add something relevant. It introduced a clause establishing that a replacement player inherits the position of the player replaced for the purposes of sanctions and dismissals, so a warning issued to the original stands against the replacement, and a player already dismissed does not get a second innings by proxy. That was written with concussion and pandemic replacements in mind, and it closed a gap that had previously been resolved by common sense rather than by text.

What cricket had before, and the incentive it created

Before 2019 a side had exactly two options after a blow to the head. Keep the player on, or lose him and continue with ten. There was no third door.

That structure produced an outcome nobody defends now. A batter who had been hit and was plainly not right would be encouraged, sometimes by himself, to carry on, because leaving the field cost his side a specialist for the rest of the match. A bowler who had taken one on the helmet in the nets would be pushed through a fitness test because the alternative was an attack of three. The cost of doing the medically correct thing was borne entirely by the team, and teams behaved accordingly.

The protocol removes that price. If the replacement genuinely restores what the side lost, then a captain deciding whether to send a groggy player off is making a purely medical decision, because the competitive consequence has been neutralised. That is the whole design intent, and every argument about the like-for-like test is really an argument about how completely the price has been removed.

The regulation entered international cricket across all three formats, and first class cricket alongside them, in August 2019. Several national boards had trialled versions of it in their domestic competitions before that.

The head injury assessment: what happens on the field and off it

Cricket's assessment is off-field and unhurried, which distinguishes it from the equivalent protocols in the collision sports.

When a player takes a blow to the head or neck, or shows signs that suggest one has been missed, the team doctor conducts an assessment. Visible signs are the first trigger: loss of consciousness, unsteadiness, a blank look, a delayed response to a simple question. Symptoms reported by the player are the second, and headache, nausea, blurred vision and a feeling of being slowed down all count. Standard cognitive screening tools are used, and the player is compared against a baseline recorded before the season rather than against a general population norm.

Cricket has an advantage the contact sports lack, which is time. A batter can be replaced at the fall of a wicket. A fielder can leave the field and be assessed properly while a substitute holds his position. There is no equivalent of the fixed assessment window used in rugby union, where the whole point of the protocol is to get a verdict before the player misses too much of a continuous game. Readers who want the contrast in detail will find it in our piece on how rugby's head injury assessment operates, and the difference between the two designs is almost entirely a function of how each sport handles stoppages.

The other consequence of that unhurried structure is delayed diagnosis. Concussion frequently declares itself late, and cricket's protocol accommodates a player who batted for an hour after the blow and only then began to look wrong. A replacement request can be made at that point.

1. 1The incident occursA player is struck on the head or neck, or shows signs consistent with concussion during play, in the warm-up or between sessions.
2. 2Assessment by the team doctorThe player is assessed off the field against a pre-season baseline, using recognised screening tools, with no fixed time limit on the process.
3. 3The team submits a requestIf concussion or suspected concussion is diagnosed, the side applies in writing to the match referee, naming the intended replacement.
4. 4The referee applies the like-for-like testThe referee compares the role the injured player would have filled for the rest of the match with the role the nominated player normally performs.
5. 5Approval, refusal or conditionsThe referee may approve the request, refuse it, or approve it while restricting what the replacement is permitted to do. There is no appeal.
6. 6The replacement takes overHe may bat, bowl, keep and captain, inherits any sanctions the injured player carried, and the injured player takes no further part in the match.

The sequence set out in the ICC playing conditions. Medical judgment sits with the team doctor; eligibility sits with the match referee.

How the request is made, and who signs it off

The application is a formality with teeth. The team submits it to the match referee, naming the player it wishes to bring on. The referee is the sole decision maker on eligibility. He is not making a medical judgment; the diagnosis belongs to the team doctor, and the referee does not second guess it. What he decides is whether the nominated replacement is an acceptable swap.

The regulation instructs the referee to approve the request ordinarily, where the nominated player is a like-for-like replacement whose inclusion will not excessively advantage his side for the remainder of the match. Two phrases in that instruction do the work. Ordinarily sets the default at yes. Excessively advantage sets the bar for saying no somewhere well above any advantage at all, because any replacement is an advantage compared with playing a man short.

The decision is final. Neither the applying side nor the opposition has a right of appeal, which is unusual in a sport that has built an entire architecture of review into its officiating. The reasoning is practical: a replacement decision has to be made in minutes, and an appeal mechanism would leave a match in limbo while a player waits to know whether he is playing.

The like-for-like test, and the argument it caused

This is the part that produces the rows, so it is worth being precise about what the test compares.

It does not compare careers. It does not ask whether the two players are of equivalent quality, and it does not ask whether the side is better or worse off in some absolute sense. It asks what job the injured player would have done for the rest of this particular match, and what job the nominated player would normally do. If those two jobs are recognisably the same, the swap goes through.

The consequence of framing it that way is that identical swaps get different answers in different situations. A batting all-rounder who has already batted and would have been asked to bowl a few overs is a different vacancy from the same player at the top of an innings with a hundred to make. A wicketkeeper injured while keeping creates a vacancy that only another keeper can fill, and no amount of batting ability substitutes for it.

The test came under sustained pressure in January 2025, when a batting all-rounder was replaced by a bowling all-rounder in an international, the replacement bowled, and a substantial argument broke out about whether the roles were genuinely equivalent. The referee had approved it under the rule as written. The governing body's response was not to defend the individual decision but to change the framework so that the same question would not arise in the same form again.

1. 1The injured player's remaining roleWhat the side would have asked of him across the rest of this match, not what his career record says he is.
2. 2The nominated player's normal roleThe job the replacement ordinarily performs for his side, judged the same way.
3. 3Whether the roles correspondA specialist batter for a specialist batter, a keeper for a keeper, a seamer for a seamer. The nominated list makes most of these obvious.
4. 4Whether the side gains excessivelyAny replacement restores something. The test is whether the side ends up better placed than it would have been without the injury.
5. 5Whether conditions can fix a mismatchRather than refusing outright, the referee may allow the replacement while limiting what he is permitted to do in the match.

The considerations the ICC playing conditions direct the referee to apply. The order is for clarity; the assessment is made as a whole.

The 2025 rewrite: five nominated players, named before a ball is bowled

The response to that controversy came in June 2025, as part of a wider package of playing condition changes that took effect in Test cricket that month and in the white ball formats the following month.

Sides must now hand the match referee a list of five nominated concussion replacements before the match begins, and the list has a fixed shape. One wicketkeeper, one batter, one seam bowler, one spinner and one all-rounder. When a concussion occurs, the replacement is drawn from that list, which means the role correspondence has already been settled in the calm of the morning rather than argued about in a corridor while a player waits.

The design solves several problems at once. It removes the incentive to name whichever player happens to suit the state of the match. It makes the vacancy and the fill visible to both sides in advance. It stops the referee from having to adjudicate a role comparison under time pressure with a partisan audience.

There is a sensible escape valve. If the nominated replacement is himself unavailable, most obviously because he has also been concussed, the referee may consider a player from outside the five under the older like-for-like protocol. The list is a strong default rather than an absolute cage.

The trade-off is a loss of flexibility, and sides with thin squads feel it most. A touring party carrying one reserve keeper has that decision made for it, while a squad of eighteen has genuine choices in every role.

20%20%20%20%20%

• Wicketkeeper1
• Batter1
• Seam bowler1
• Spin bowler1
• All-rounder1

The composition required by the ICC playing conditions from 2025. Each role is a single named player; the figure shows the structure, not relative importance.

Show the numbers

The five roles a side must nominate before the match

Item	Value
Wicketkeeper	1
Batter	1
Seam bowler	1
Spin bowler	1
All-rounder	1

The stand-down period, and why it exists

The same 2025 package attached a minimum stand-down of seven days to a diagnosis of concussion. A player diagnosed during a match is unavailable for that period, whatever he says about how he feels and whatever the fixture list looks like.

The medicine behind that number is about the second impact rather than the first. A brain recovering from a concussion is more vulnerable to another one, and the outcomes from a second blow during the recovery window are disproportionately worse than the arithmetic of two separate incidents would suggest. A fixed floor removes the negotiation entirely, which is the point. Players are poor judges of their own concussions, and the pressure to be available for a Test that starts in four days is not a pressure any individual should have to weigh.

Seven days is a minimum, not a treatment plan. A graduated return, where a player progresses through rest, light exercise, sport-specific work and finally contact and match play, sits on top of it and can take considerably longer. The regulation sets the earliest permissible date; the medical staff set the actual one.

What the replacement inherits, and what he cannot do

A concussion replacement is not a fresh start, and several inherited restrictions catch people out.

If the injured player had been suspended from bowling, for two beamers or for running on the pitch, his replacement cannot bowl in that innings either. The suspension attaches to the position rather than to the person, which is exactly what the Laws' replacement clause was tightened to establish.

Warnings carry across in the same way. If the side had been warned about a particular offence, the replacement plays under that warning rather than under a clean sheet. A player who has already been dismissed in an innings cannot come back as somebody else's replacement and bat again.

The injured player takes no further part in the match. That is absolute. He does not return if he feels better on day four, and he does not come back to bowl a spell in the second innings. Once the replacement is approved, the swap is permanent for that fixture.

Both players count as having played. Runs, wickets, catches and dismissals all stand under the name of whoever produced them, and both appear in the scorecard. That is a departure from the ordinary substitute, who leaves almost no statistical trace, and it is worth knowing when reading a match record that appears to show twelve players in a side. Our guide to reading a scorecard properly covers the other places where a scorecard says more than it appears to.

The conditions a referee can attach instead of refusing

The binary framing of approved or refused misses the most interesting power the referee holds, which is to say yes with limits.

Where the referee judges that a replacement performing his normal role would hand the side too much, he may impose conditions on the identity or the involvement of that player rather than turning the request down. In practice that means allowing a player onto the field while restricting what he does with it, most obviously by preventing him from bowling when the vacancy he is filling was a batting one.

This is the pressure valve that keeps the protocol humane. A flat refusal would leave a side a man short, which reintroduces the exact penalty the rule exists to abolish. A conditional approval restores the numbers without restoring an advantage the side did not have. The nominated list makes conditions rarer than they used to be, because the mismatches that provoked them are now largely designed out.

How the rule differs below international level

National boards write their own versions, and the differences are real enough to matter when reading about a domestic match.

Some competitions run the protocol without pre-nomination, on the original like-for-like model. Some vest the decision in a match referee, others in the umpires where no referee is appointed. Stand-down periods vary with national medical guidance. Franchise leagues bolt the protocol onto their own squad rules, and where a competition already permits a tactical substitution the two mechanisms have to be kept apart, since one is a medical entitlement and the other is a strategic choice. The distinction is easy to blur when watching, and our explainer on the tactical substitute used in the Indian Premier League sets out how a rule with a superficially similar effect works on entirely different reasoning.

Women's international cricket runs the same ICC protocol as the men's game, with the same nomination requirement and the same stand-down. That symmetry is deliberate, and it matters more than it might appear, because squad sizes in the women's game have historically been tighter and a rule requiring five named reserves has a sharper effect on a smaller touring party. The way resourcing differences shape the women's international programme is covered in our piece on how the women's game has grown.

At recreational level, many leagues have adopted a simplified version, often permitting a straightforward replacement with no like-for-like test at all on the grounds that a Saturday XI is not gaining a competitive edge worth policing. The safety half of the rule matters far more there than the fairness half.

Why the short ball, the helmet and the protocol arrived together

The protocol did not appear in isolation. It came at the end of a decade in which the game reconsidered the whole business of bowling at a batter's head, and the two developments are best read together.

Helmets changed first. Modern designs are tested against a standard that measures whether the ball can penetrate the gap between the grille and the peak, which is the failure mode that caused the worst injuries in the older equipment. Neck protectors, clipped to the back of the helmet, address the exposed area below the shell. Neither eliminates concussion, because concussion is caused by the brain moving inside the skull rather than by the skull being broken, and no amount of padding stops deceleration. What better equipment did was shift the injury profile from fractures and lacerations towards the concussive end, which is harder to see and easier to play through.

The laws governing short bowling changed alongside. There are limits on how many balls above shoulder height a bowler may send down in an over, and separate protections for a batter judged incapable of defending himself. The reasoning behind those limits, and the way umpires apply them, is set out in our piece on what the bouncer rule actually permits. None of that removes the short ball from the game, and nor is it meant to: the bouncer is a legitimate delivery and the contest it creates is part of what Test cricket is for.

What all of it means together is that a modern side plans for head injuries the way it plans for hamstrings. The blows still land, the diagnoses are more likely to be made rather than missed, and a protocol that used to be invoked rarely is now part of the ordinary furniture of a match.

What the rule does to squad selection

The 2025 nomination requirement turned the protocol into a selection problem, and the good sides treat it as one.

A touring party has to be built so that all five nominated roles can be filled by somebody the side would be content to see walk out. That is straightforward for a squad with two keepers and four seamers, and awkward for a squad that has been trimmed to a bare fifteen with one spinner. The reserve spinner nominated as a concussion replacement is a player who might not otherwise have travelled at all, and the requirement gives selectors a reason to carry him.

It also changes what a nomination signals. Because the list goes to the match referee before the toss, both sides know who has been named in each role. That is a small piece of information about how a team sees its own reserves, and it occasionally reveals more than the eleven does: a side that names a young all-rounder rather than an experienced one is telling you something about who is next in line.

The subtler effect is on the eleven itself. Where a side previously chose a batter who could bowl a little on the reasoning that he covered several eventualities, the nominated list handles some of that cover separately. It does not make flexible cricketers less useful, but it does mean a squad's depth is now audited in public before every match rather than discovered during one.

What separates a concussion replacement from every other kind of substitute

Cricket now has several ways of putting a different player on the field, and they are constantly confused with one another.

The ordinary substitute is the oldest. He comes on because a player is off the field for any reason, he fields, and that is the extent of his rights. He may not bowl, he may not bat, and he may not captain the side. A catch he takes counts, and beyond that he leaves nothing behind.

The runner, once permitted for an injured batter, has been removed from international cricket entirely. A batter who cannot run now bats without help or retires hurt.

The retirement categories are their own tangle. A player who retires hurt may resume his innings later if he is able. A player who retires for any other reason may only resume with the opposing captain's consent, and is otherwise recorded as out.

The concussion replacement sits apart from all of these because it is the only mechanism that produces a full replacement rather than a partial one, and the only one triggered by a diagnosis rather than by a captain's preference. That combination is why it needed a like-for-like test in the first place. An ordinary substitute needs no such test, because he cannot do anything worth policing.

Where the protocol still argues with itself

Three tensions remain unresolved, and they are worth recognising because they surface every time the rule is in the news.

The first is that the like-for-like test measures roles rather than value. Two players can occupy the same role and be very differently useful, and no framework built on job titles can capture that without becoming a selection committee.

The second is that the doctor making the diagnosis is employed by the team that benefits or suffers from it. Independent match day doctors exist in other sports for exactly this reason, and cricket has not gone that far at every level. The regulation manages the conflict by making the diagnosis unreviewable rather than by removing it.

The third is the difficulty of diagnosing a concussion at all. Research into blood markers continues, and the sport will adopt an objective test the moment a reliable one exists. Until then there is no blood test and no scan that settles it, and the assessment relies on symptoms a competitive athlete has every incentive to understate. A protocol can only ever be as good as the honesty of the answers it collects, which is why the fixed stand-down and the pre-nominated list both work by removing choices rather than by improving judgment. The way governing bodies have handled that problem across sports is covered in our piece on the laws and regulations every follower of cricket should know.

What to watch for when it happens

A few signals tell you what is going on before the broadcast catches up.

If a batter is struck on the helmet and the physio comes out with a card rather than a spray, an assessment is starting. Watch whether the player leaves at the next fall of a wicket rather than immediately, because that is the protocol working as designed rather than a side stalling.

When a replacement is announced, listen for the role rather than the name. Under the nominated list system, the role tells you which of the five slots was used, and it tells you what the referee has already accepted. If the announcement includes a restriction, a note that the replacement will not bowl, then the referee has attached conditions and judged the straight swap too generous.

Watch the fielding side too. A team that has lost a bowler to the protocol has to redistribute overs it had already allocated, and the captain who suddenly has four bowlers instead of five will start rationing them from the moment the replacement is confirmed. The effect on a fourth innings, where a side needs its best bowler fresh at the right moment, can outlast the injury by two days.

And watch the following fixture. A player who left the field with a head injury and appears three days later has, by the current regulation, not been diagnosed with concussion, whatever the highlights package implied. The stand-down is the clearest public signal there is of what the medical staff actually concluded.

The protocol is a good piece of rule making because it changes an incentive rather than issuing an instruction, and the sides that use it well are the ones that treat the nominated list as a selection decision rather than a form to fill in. That kind of squad thinking is the same one covered in our piece on what an all-rounder is really worth to a side. More of our writing on the game sits in the cricket section, and the blog carries the same treatment of rules and tactics across every sport we cover.