What is DRS in cricket? Explaining the decision review system

The Decision Review System, or the DRS in cricket, is a technology-based system introduced in cricket to improve the accuracy of decision-making during matches.

The purpose of the DRS is to assist on-field umpires in making transparent decisions and remove any errors that they might have committed when giving their initial verdict.

The DRS in cricket was initially implemented in Tests in 2008, during India's series against Sri Lanka, with Virender Sehwag becoming the first international player to be given out under the review system.

Since then, the DRS in cricket has undergone significant improvements under the supervision of the International Cricket Council (ICC).

While Test cricket was the first format to adopt the DRS, it wasn't until 2011 that the 50-over format embraced the system. T20 Internationals introduced the DRS even later, in 2017.

What is the Decision Review System? DRS explained

When a team chooses to utilize the DRS in cricket, they challenge the decision made by the on-field umpire. The incident is then reviewed by the third umpire, who employs a number of slow-motion camera angles along with ball tracking or edge detection technologies, where relevant.

To request a DRS review, either the captain of the fielding team or the batsman in the middle must signal ‘T' with their hands within a 15-second window after the on-field umpire's decision. The query is then sent to the third, or the TV, umpire.

However, if the time limit is exceeded, the on-field umpire has the right to deny the review request. Moreover, if the on-field umpires suspect any form of external assistance, they can refuse the review.

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A famous example of this was in 2017 during the Bangalore Test against India when Steve Smith seemingly looked at the dressing room before taking the DRS on day four. The umpires, on being informed of the action by then-India skipper Virat Kohli, denied Smith from taking the DRS. Smith later termed this incident as a “brain fade”.

How does the DRS in cricket work?

The DRS in cricket process begins by verifying the fairness of the delivery, specifically checking if the bowler overstepped or not. Once the legality of the delivery is confirmed, the third umpire proceeds to review the specific aspect of the dismissal that has been challenged.

However, the umpire ultimately examines all modes of dismissal.

For instance, in the case of challenging an LBW decision, the TV umpire looks at whether the ball made contact with the bat using tools such as Ultra-edge and Hotspot.

If inconclusive, the third umpire proceeds to ball-tracking, utilizing the renowned Hawkeye technology to determine the projected trajectory of the ball after it hits the pads.

Regarding an LBW decision, the third umpire can overturn the on-field umpire's decision only if the ball is pitched in line, impacts the pads in line, and is projected to hit the stumps.

If a team contests a caught decision, the third umpire examines whether the ball hit the bat using Hotspot and Ultra-edge. If contact is detected, the cleanliness of the catch is reviewed.

However, if the ball did not touch the bat but struck the pads, the third umpire follows the LBW process to eliminate other possible modes of dismissal.

What is the umpire's call rule in DRS in cricket?

It is important to note that technology is not flawless, which is why the DRS in cricket incorporates the concept of the umpire's call.

The Hawkeye tracking system in DRS offers multiple projected paths for the ball, and the trajectory displayed on the screen represents one of the possible paths the ball could have taken if it hadn't hit the pads.

The introduction of the umpire's call rule by the ICC ensures that the on-field umpire receives the benefit of the doubt and isn't solely reliant on technology.

The umpire's call comes into play when there is a challenge for a LBW decision. If the fielding team requests a review for an LBW decision, the on-field umpire goes it to the TV umpire, who upholds the on-field decision for marginal calls.

This usually occurs when the ball tracking shows that the ball just clips the stumps. To overturn the on-field decision, more than 50% of the ball must be projected to hit the stumps.

How many DRS in cricket is allowed per team in a match?

When the umpire's call is upheld, the team that challenged the decision does not lose their review.

The number of DRS in cricket reviews allowed for a team has undergone changes since its introduction. In Test cricket, each team is permitted three unsuccessful player reviews per innings.

Following the Covid-19 pandemic, this limit was increased by one in all three formats to accommodate a shortage of experienced and local umpires due to travel restrictions.

In white-ball cricket, two unsuccessful reviews can be used per innings, while there is no limit for successful DRS reviews.

DRS in cricket controversies in the past

The DRS has not been without controversies. Instances such as Sachin Tendulkar's LBW decision in the 2011 World Cup semi-final against Pakistan, Joe Root's caught-behind in a 2014 Test match, and Smith surviving an LBW appeal in the 2021 Test against India have sparked debates surrounding the system.

India found themselves embroiled in another DRS in cricket controversy during a tour of South Africa. In the third Test, Dean Elgar successfully overturned an LBW decision that initially seemed to indicate the ball from Ravichandran Ashwin would hit the leg stump.

However, the ball tracking revealed that it would just touch the top of the leg stump. Frustrated by the decision, the Indian players voiced their dissatisfaction on the field through stump microphones and even accused the host broadcasters of unfair tactics.

Similarly, in a Test match between India and Australia in Sydney in 2021, the DRS in cricket sparked a heated debate after a perplexing fourth stump appeared during ball tracking.

To the naked eye, it appeared that the ball would miss the leg stump by a considerable margin after making contact with Smith.

In conclusion, the DRS was introduced in cricket to enhance decision accuracy by enabling teams to challenge on-field umpires' decisions using various technologies. While controversies and debates have surrounded the system, the DRS continues to play a significant role in promoting fairness and transparency in the game.

Rules and usage of DRS in each format


Every decision reviewed using DRS involves fixed steps followed by the third umpire as part of the DRS in cricket rules. After the on-field umpire gives his decision, the challenging team has a time of 15 seconds to make its decision if they want to opt for the DRS call or not. The fielding captain or the batsman declared out needs to signal a “T” sign to the onfield-umpire to review the decision.

As it happens, the third umpire checks if it's a legal delivery in case the bowler has overstepped before proceeding with the replays at the business end. If the delivery is fair and legal, then the third umpire proceeds to the other end involving the heart of the event.

DRS in cricket

The third umpire is facilitated with Ultra-Edge/Real-Time Snicko (RTS) and HotSpot as two means to check if the ball has hit the bat in case of an lbw or an appeal for a catch.

The HotSpot technology works on the process of heat caused by the interaction between bat and ball, which will immediately result in a spot on the bat in case of a possible edge. Whereas, UltraEdge or RTS uses sound to indicate a deviation or spike when the ball is close to the bat.

How many DRS reviews in Test Cricket, ODIs, and T20 Cricket?

ICC has also fixed the number when a team can opt for a valid DRS in cricket call based upon the format. In Test cricket, each team is awarded two unsuccessful reviews in an innings.

In the case of ODIs and T20 matches, only one unsuccessful review is permitted per team in an innings. However, in the Covid era, due to home umpires, each team was allowed to use a review thrice in their innings during a Test match while two reviews were allowed in an ODI.