Players may care for the ball, but they may not unfairly change it.

What ball tampering means

Ball tampering is the unfair changing of the match ball's condition. It is not limited to one famous method such as sandpaper, bottle tops, or scratching the seam. The question is whether a player has taken an action that changes the ball outside the limited actions the Laws permit.

The umpires do not have to prove that the ball moved differently afterwards. If they consider that a player's action did not comply with the allowed forms of ball care, they treat the ball's condition as unfairly changed and apply the Law 41 procedure.

What fielders are allowed to do

A fielder may polish the ball on clothing if no artificial substance is used, the only natural substance used is sweat, and the polishing does not waste time. Mud may be removed from the ball, but only under umpire supervision. A wet ball may be dried on a cloth that the umpires have approved.

Those permissions are narrow. Ordinary shining on clothing is allowed only within those limits. Anything added to the ball, anything used to rough it up, or anything done away from the umpire's permitted process can become a ball-condition offence.

Common examples of unfair changes

Illegal changes can include scratching, picking, scuffing, rubbing the ball on the ground, interfering with the seam, using an object, applying an artificial substance, or using an unauthorised method to shine or dry the ball. A batter is also not allowed to wilfully damage the ball except in carrying out normal batting duties.

The Laws deliberately use broad language because tampering methods vary. Officials look at the action and its likely effect on the ball, not just whether a particular named tool or substance was used.

How officials monitor the ball

The umpires make frequent and irregular inspections of the ball. They also inspect it immediately if they suspect anyone has attempted to change its condition outside the permitted actions.

Because the umpires control the match balls, they take possession of the ball at wickets, intervals, and interruptions. That control helps them compare wear, manage any replacement, and keep the ball from being altered during stoppages.

The first unfair change brings five runs

If the umpires decide that a member or members of either side have unfairly changed the ball, the opposing side receives 5 penalty runs. The umpires also report the occurrence after the match to the relevant team executive and governing body.

The penalty applies whether or not the ball is actually replaced. Replacement is a separate choice given to the opposing captain. If the batting side is the non-offending side and its captain is not available, the batters at the wicket may act for the captain in deciding whether a replacement is wanted.

The replacement should match the old wear

When replacement is requested after unfair ball-condition change, the umpires select and bring into use a ball with wear comparable to the previous ball's condition immediately before the offence. The non-offending side does not simply receive a brand-new ball as compensation.

This matters because ball age is part of cricket's balance. A 45-over-old red ball, a nearly new white ball, and a ball that has gone soft late in an innings are not interchangeable. The replacement should be as close as practical to the state the ball had before it was unfairly changed.

Repeated tampering can remove a bowler

If the umpires agree that the same team has a further instance of unfairly changing the ball in the match, they repeat the replacement and 5-run penalty process. If the further offence is by the fielding side, the bowler who delivered the preceding ball is suspended from bowling immediately and may not bowl again in the match.

If that suspension happens before an over is complete, another bowler must finish it. The replacement bowler cannot have bowled any part of the previous over and cannot bowl any part of the next over.

Normal ball replacement is different

A ball can also be replaced without misconduct. If the ball cannot be found or recovered, or if the umpires agree it has become unfit for play through normal use, they replace it with a ball that has comparable wear to the old one.

That is not a penalty situation. The umpires inform the batters and the fielding captain, but there is no automatic 5-run award just because a ball is lost, damaged by normal use, or no longer fit for play.

A new ball is not the same as a replacement ball

At the start of each innings, either captain may demand a new ball unless a different pre-match agreement applies. In matches of more than one day's duration, the fielding captain may demand a new ball once the old ball has been used for at least 80 overs, excluding part overs.

Limited-overs competitions and professional playing conditions can add their own ball-management rules, such as using more than one new ball in an innings. Those details vary by format and competition, so a general Laws explanation should not assume the same new-ball procedure everywhere.

How to read a ball incident

1. Ask whether the ball was changed by normal play, normal wear, loss, or a player's action.
2. If a player acted on the ball, check whether the action fits the limited permitted care: polishing with sweat only, supervised mud removal, or drying on an approved cloth.
3. If the action falls outside those permissions, the umpires may treat the ball as unfairly changed.
4. Apply 5 penalty runs to the opposing side and ask whether that side wants the ball replaced.
5. If it is a further offence by the fielding side, suspend the bowler who delivered the preceding ball from bowling again in the match.

Misunderstandings to avoid

• "Only sandpaper is ball tampering" is wrong. Any unauthorised action that changes the ball's condition can be unfair play.
• "A replacement means a new ball" is wrong. The replacement should have comparable wear to the ball before the problem.
• "The batting side always gets the penalty" is wrong. The opposing side gets the 5 penalty runs, so a fielding side can receive them if the batting side committed the offence.
• "The ball must be replaced after tampering" is too broad. The opposing captain is asked whether replacement is wanted, but the 5-run penalty applies either way.
• "A lost or damaged ball is automatically misconduct" is wrong. Normal loss or normal unfitness is handled as replacement without a penalty.

Source material

• MCC Law 41: Unfair play
• MCC Law 4: The ball
• MCC Law 20: Dead ball
• MCC Laws of Cricket
• ICC Playing Conditions