What is DRS in Cricket? Explanation for Beginners

If a team is unhappy with a decision made by the on field umpires, they have the option for the TV umpire to take a look at the call. This is often referred to as DRS in cricket: By using available technology, that TV umpire can establish whether that original decision should be upheld or overturned.

DRS or UDRS is an acronym which stands for (Umpire) Decision Review System. It is a slow motion TV technology-based referral process which can be used by either side in a cricket match to assist either the umpires or referees in their decisions.

In Short

DRS stands for Decision Review System which was introduced into test cricket in 2011. It was implemented to help umpires make tight calls over dismissals such as LBW, Run Out and Stumped.

Both teams are allocated a certain number of referrals for each innings and, if they feel that an incorrect decision was made by the umpires on the field, they have the right to ask for the Decision Review System to intervene. The standing umpires will then refer the decision to the TV umpire in order to confirm or overturn the original call.

Using slow motion TV replays and other technology, the Television umpire will then have the final say. It’s a significant development in the game which is in place to make sure that no major errors are made on the field.


How Does the Umpire Decision Review System Work?

During play, umpires are called upon to make decisions regarding dismissals. There are currently 10 ways in which a player can be given out and, in most cases, the dismissal will be obvious. If a batsman is bowled or caught on the boundary and the delivery is a legal one, the fielding side will not appeal and the batter should simply walk off the field.

In other cases, most notably Leg Before Wicket (LBW), the decision is not an obvious one and the fielding side will appeal to the standing umpire. In turn, the umpire will assess what has happened on the field and he or she will decide whether the batsman is out or not out.

cricket drs

If either the fielding side or the batsman do not agree with the decision, they have the right to refer to DRS. Referrals are also typically made by players for caught behind decisions.

Umpires also have the option to refer to DRS in cases of line decisions where the fielding team has appealed for a run out or stumping. Referrals would also be made to the TV umpire in certain other instances – for example, if the standing officials need confirmation on a fair catch.

The DRS system looks at all the potential factors that are involved in the decision making process. In cases where players are asking for a referral for caught behind, it’s a fairly straightforward process for the TV Umpire. Usually, the only question to consider is whether or not the batsman has hit the ball with their bat or gloves.

Ultra edge is the equipment used to uphold or overturn these decisions. Sound waves show up to interfere with a flat line and it should be clear to the umpire if those deviations are caused by the bat or ball onto the glove.

For leg before wicket decisions, the TV umpire has to consider other factors that are instrumental in terms of the LBW law. Here, TV slow motion replays will confirm where the ball pitched, whether it hit the batsman in line and whether or not it is going on to hit the stumps.

A batsman cannot be given out LBW if they have hit the ball so the TV umpire will also use ultra edge to determine whether bat or glove is involved before the ball hits the batsman’s pad.

For line decisions, specifically run outs and stumpings, it’s a simple case of using slow motion TV replays to determine whether the bat or any part of the batsman’s body is behind the line when the wicket is broken.

Umpire Review and Player Review

There are two types of review made to the TV Umpire under the UDRS system. Umpire Reviews and Player Reviews can both take place during the course of a cricket match. A player review will occur if the batsman or the fielding side are unhappy with the original decision. The TV umpire will then be asked to adjudicate.

In contrast, an umpire review can be made by the two standing officials and this will only happen if they do not have enough evidence to come to a conclusion on the field. For example, run outs and stumpings happen very quickly in real time. In most cases it’s impossible for the umpire to accurately judge whether the batsman had made their ground at the exact point that the wicket has been broken. An umpire review will therefore allow the third official to use slow motion TV replays in order to make the correct decision.

Similarly, the two standing umpires won’t always be able to tell whether a catch has been taken fairly. A fielder may claim a catch low down to the grass but has the ball come in contact with the ground before that fielder had control? If that question is impossible to answer on the field, an umpire referral to the TV umpire can clear the matter up.

Umpire’s Call

UDRS also has a feature known as Umpire’s Call which relates to marginal decisions. In cricket, the word of the umpire has always been final and this phenomenon helps to maintain that ethos.

Umpire’s Call refers to LBW decisions and, specifically, where the ball hits. It can either relate to where the ball pitches, where it strikes the batsman and where it strikes the wickets. If those points are marginal and less than 50% of the ball is where it needs to be, the decision will remain with the on field umpire.

Walking through the LBW process, the first point to consider is where the ball has pitched. If it pitches outside leg stump then the batsman cannot be given out leg before wicket. Following a player referral for LBW, ball tracking technology will look at this question in the first instance. At least 50% of the ball needs to pitch in line for any decision to be overturned by the TV umpire. If less than 50% pitches in line with leg stump, the LBW decision stays with the on field umpire.

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The next part of the LBW process relates to where the ball hits the batsman. The relevant law states that a batman cannot be given out LBW if they are struck outside off stump – as long as they are playing a shot. The next steps are similar to those relating to the pitch of the ball. If at least 50% of the ball hits the batsman in line, the decision can be overturned by the TV umpire. If not, that decision will remain with the on field officials.

The final point to consider is whether or not the ball would go on to hit the stumps. If at least 50% of the ball makes contact with the stumps, there is potential for the TV umpire to overrule a decision made by the on field officials. If less than 50% strikes the stumps, Umpire’s Call is in play.

UDRS Technology

When a referral is made on the field, either by a player or an umpire, the TV umpire has a range of technology at their disposal. First of all, they will need television replays: The first job of a slow motion TV replay is to check that the delivery in question is legal and that the bowler hasn’t bowled a no ball.

Once that has been established, a TV replay can check whether the ball has hit the batsman’s bat or glove. On occasions, it can be obvious whether or not the bat was involved but in most cases, the TV umpire will need a little extra help. This is where the next part of their equipment comes into play. Ultra Edge detects soundwaves and, when used in conjunction with those slow motion TV replays, the umpire can detect whether or not the ball has hit the bat or glove.

Microphones can also play a part in caught behind decisions. These would be used in conjunction with a real time replay and may bring up an obvious sound of the ball hitting the bat on its way to the wicket keeper.

In some cases, all three items of technology will be used by the umpire. All dismissals will rely on TV replays to an extent while ultra edge is the second most common option.


One possible issue with UDRS technology is the fact that it claims to only be 90% accurate. That leaves a 10% margin of error and there have been occasions when a collective naked eye feels that clear mistakes have been made.

One of the most controversial discussions around DRS involves the question of a fair catch. TV replays haven’t yet been able to adequately establish whether or not the ball has hit the ground before it comes to rest in the fielder’s hands. There is an unavoidable ‘foreshortening’ of the lens and, even with close up, zoomed images, it isn’t completely clear.


The controversy here mainly relates to the on field umpires and the fact that they are required to make a ‘soft signal.’ Based on what they have seen on the field, the standing umpires are required to suggest to the TV official whether or not they think the catch was taken fairly. The soft signal given is for ‘out’ or ‘not out’. The TV umpire then has to find sufficient evidence to overturn that initial decision.

Players feel that standing officials should simply say that they don’t know and that the TV official has to make the final decision. That isn’t really a problem with UDRS but it is a question to be addressed in relation to the laws surrounding TV replays.


The introduction of technology has been seen in other sports for a number of years. Tennis, rugby and football are obvious examples and it was only natural that cricket followed. The advantages of using DRS are clear: It is there to deal with major mistakes made by the on field officials and any obvious errors can be overturned and provided with the correct outcome.

At the same time, the authority of the standing umpires remains. Thanks to umpires call, the officials directly involved still get to have their say over marginal decisions. The fact that UDRS has a 90% accuracy rate is one potential downside and this is an area which can be improved in the years to come. For now, the majority of spectators, players and officials see the Decision Review System as a welcome addition to cricket.