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Decision Review System
Decision Review System
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Decision Review System
Ball tracking visualisation in 2020
AbbreviationDRS
StatusActive
Year started2008
First published2008
OrganizationInternational Cricket Council (ICC)
Base standardsBall tracking: Hawk-Eye or Virtual Eye

Sound analysis: Real Time Snicko

Infra-red imaging: Hot Spot (Australia-only)
Batters and fielders wait for a decision to be shown on the big LED screen.

The Decision Review System (DRS), is a technology-based system used in cricket to assist the match officials in their decision-making. On-field umpires may choose to consult with the third umpire (known as an Umpire Review), and players may request that the third umpire consider a decision of the on-field umpires (known as a Player Review).

The main elements that have been used are television replays, technology that tracks the path of the ball and predicts what it would have done, microphones to detect small sounds made as the ball hits bat or pad, and infra-red imaging to detect temperature changes as the ball hits the bat or pad.

While on-field Test match umpires have been able to refer some decisions to a third umpire since November 1992, the formal DRS system to add Player Reviews was first used in a Test match in 2008, first used in a One Day International (ODI) in January 2011, and used in a Twenty20 International in October 2017.

History

[edit]

DRS was preceded by a system to allow on-field umpires to refer some decisions to the third umpire to be decided using TV replays, in place since November 1992.

Sri Lankan born Lawyer Senaka Weeraratna conceived the concept of 'Player Referral' which was first published as a letter to the Editor of the 'Australian' newspaper on March 25, 1997. The ICC adopted the 'Player Referral'concept in 2006.[citation needed]

The Player Referral system was first tested in an India v. Sri Lanka match in 2008,[1][2] and was officially launched by the International Cricket Council (ICC) on 24 November 2009, during the first Test between New Zealand and Pakistan at the University Oval in Dunedin.[3][4] It was first used in One Day Internationals (ODI) in January 2011 during Zimbabwe's tour of Australia.[5] The ICC initially made the UDRS mandatory in all international matches,[6] but later made its use optional, so that the system would only be used if both teams agree. The ICC has agreed to continue to work on the technology and will try to incorporate its use into all ICC events.[7]

In October 2012, the ICC made amendments on lbw protocols, increasing the margin of uncertainty when the ball hits the batsman's pad.[8] In July 2016, the rules were amended once again, reducing the margin of uncertainty.[9][10] The updated rules were first used in the ODI match between Ireland and South Africa in September 2016.[11]

In September 2013, the ICC announced that for a trial period starting in October 2013, a team's referrals would be reset to two after 80 overs in an innings in Test matches. Previously each team had a maximum of two unsuccessful reviews per innings.[12]

Starting in November 2014 from Australia's ODI series versus South Africa, the field umpires' communications have also been broadcast to the viewers. Whenever a decision is reviewed by the TV umpire, their communication with the field umpire can be heard.[13]

In February 2013, the ICC agreed the use for all future ICC World Twenty20 tournaments, with one review per team.[14] The first T20 tournament to use the technology was the 2018 ICC Women's World Twenty20.[15] It was used in the knockout stages of 2017 Indian Premier League, which was the first time DRS used in a T20 league. DRS was used for the first time in a Twenty20 International in the 2014 ICC World Twenty20.[16]

Under the new ICC rules of November 2017, there would no longer be a top-up of reviews after 80 overs in Test matches, and teams will have only 2 unsuccessful reviews every innings. However, teams would no longer lose a review for an "umpire's call" (a ruling in which the on field's umpire's ruling stands due to inconclusive data) on an LBW review.

In 2020, the requirement to appoint neutral match officials was temporarily suspended due to the logistical challenges with international travel during the COVID-19 pandemic. Following from this change, the number of unsuccessful reviews per test innings was raised from 2 to 3 keeping in mind that there may be less experienced umpires on duty at times.[17]

From 1 June 2023, the "soft-signal" requirement for umpires when referring catches was scrapped as they were "unnecessary and at times confusing".[18][19]

Components

[edit]

The components of DRS are:

A typical "snick" shown in the Snickometer display
A typical edge shown in the Hot Spot display
  • Video replays, including slow motion.
  • Hawk-Eye,[20] or Virtual Eye (also known as Eagle Eye): ball-tracking technology that plots the trajectory of a bowling delivery that has been interrupted by the batter, often by the pad, and can predict whether it would have hit the stumps.
  • Real Time Snicko (RTS) or Ultra-Edge[21][22][23] (Hawk-Eye Innovations): directional microphones to detect small sounds made as the ball hits the bat or pad. The use of the original Snickometer was superseded by Real Time Snicko in 2013.[24][25][26][27][28] RTS is calibrated each morning without needing manual syncing during play.[29] The third umpire interprets RTS/Ultra-Edge data by checking if an audio spike occurs on the frame before, on the frame, or the frame after the ball passes the bat.[30][31]
  • Hot Spot: Infra-red imaging system that shows where the ball has been in contact with bat or pad. Improved cameras were introduced for the 2012 season.[32] The system came under fire after the 2013 Ashes in England.[33] It was claimed that using silicone tape prevented faint edges being picked by Hot Spot, which was later confirmed by a MIT report.[34]
Comparison of ball-tracking technology
System No. of cameras Camera framerate
Hawk-Eye 6[35] 340 fps[35]
Virtual Eye (Eagle Eye) 4[36] 230 fps[36]

System

[edit]

Umpire reviews

[edit]

In many cases, the event occurs in a fraction of a second. At their discretion, on-field umpires may request the Third Umpire reviews the following dismissal decisions:[37]

  • Run out. If the on-field umpires are unable to decide if the batsman is out, they may request the third umpire to ascertain whether the batsman had made it home. Also the case where both batsmen have run to the same end and the on-field umpires are uncertain over which batsman made his ground first. An example of this was the Third Test between New Zealand and the West Indies in 2006.[38]
  • Caught and Obstructing the field if both umpires are unsure. In some cases the fielder may catch the ball a few inches above ground level. If the umpire's vision is obscured or is unsure if the ball bounced before the fielder caught the ball, he can refer the decision. The third umpire also checks whether the delivery was a no-ball and whether the batsman hit the ball.
  • Whether the delivery causing any dismissal was a no-ball.

Note the on-field umpires may not request the Third Umpire review an LBW decision (apart from whether the delivery was a no-ball).

The on-field umpires may also request the Third Umpire reviews the following:

  • Boundary calls (to see if a batter hit a four or a six). In some cases the ball may bounce just a foot inside the boundary rope resulting in four runs. If the umpire needs to ascertain if it had been a 4 or a 6, he may consult the third umpire. Near the boundary, often a fielder may dive to save the ball from travelling beyond the boundary. If the fielder makes any simultaneous contact with the boundary and the cricket ball, 4 runs are declared. A third umpire may also be consulted in such a case.
  • Whether the ball has hit cameras on or over the field of play.

Umpire Reviews are also available to the on-field umpires when there is a Third umpire but the full UDRS is not in use. In this case, the Third umpire uses television replays (only) to come to a decision, and not the additional technology such as ball-tracking.[39]

Player reviews

[edit]
Scoreboard showing number of DRS unsuccessful Player Reviews remaining for India (2) and England (2)
Scoreboard showing number of DRS unsuccessful Player Reviews remaining for India (2) and England (2)

A fielding team may use the system to dispute a "not out" decision and a batting team may use it to dispute an "out" decision. The fielding team captain or the batter being dismissed invokes the challenge by signalling a "T" with the arms or arm and bat. A challenge is only used in situations that did or could result in a dismissal: for example, to determine if the ball is a legal catch (making contact with the batter's bat or glove and not touching the ground before being held by a fielder), or if a delivery made the criteria for an LBW dismissal.

Once the challenge is invoked, acknowledged, and agreed, the Third Umpire reviews the play.

Each team can initiate referrals until they reach the limit of unsuccessful reviews.[40] This limit is three unsuccessful review requests per innings during a Test match, and two unsuccessful review requests per innings during a One Day International or T20I (this limit was temporarily raised to three per innings for tests and two for one-day matches from July 2020 as a COVID-19-related rule change but has since become permanent[41]). From 2013 until September 2017, the number of reviews available for a team in a Test innings was topped-up to two after 80 overs. From October 2017, if the on-field decision remains unchanged because the DRS shows "umpire's call", the team will not lose its review.[42][43][44]

Umpire's call

[edit]

As DRS is designed to allow for clear errors to be corrected, umpires call is utilised in situations where there are doubts in the accuracy of the technology, or the decision is not a clear error. This is utilised when determining LBW.

When determining LBW, the umpire must be sure of multiple factors. Where the ball "pitches" or lands on the pitch, where the ball impacts on the player, if the player has hit the ball with their bat before it impacts the player, as well as if the ball would have gone on to hit the stumps. This is usually split into three sections. "Pitching", "Impact" and "Wickets".[45]

Umpire's call is not utilised for where the ball pitches, or if the player has hit the ball first.

For a decision to be Umpire's call, the ball must either be judged to impact the player with less than 50% of the ball in line with the stumps, or less than 50% of the ball must be judged to be hitting the stumps, either horizontally or vertically.

In addition, due to issues with the technology available, any impact with the player 300 cm or more from the stumps, or less than 40 cm between the ball pitching and impact the player, is also judged to be the Umpire's call.[46]

If either impact or wickets is judged umpires call. The umpire's original decision is upheld and the reviewing team retains their review.[47]

The implementation of the Umpire's call has been noted in other sports whereby similar issues have arisen in the case of highly-marginal decisions (i.e. not a "clear mistake) which are perceived to be unfairly decided by forensic and technical means.[48][49][50]

On April 4, 2021, in the International Cricket Council committee meeting led by Anil Kumble, the height margin of the Wicket Zone was lifted to the top of the stumps to ensure the same Umpire's Call margin around the stumps for both height and width.[51]

Final decision

[edit]

The third umpire then looks at various TV replays from different angles, comes to a conclusion, and then reports to the on-field umpire whether their analysis supports the original call, contradicts it, or is inconclusive. The on-field umpire then makes the final decision by either re-signalling a call that is standing or revoking a call that is being reversed (usually by placing their crossed hands on shoulders) and then making the corrected signal. Only clearly incorrect decisions are reversed; if the Third Umpire's analysis is not within established margins of error or is otherwise inconclusive, the on-field umpire's original call stands.[52]

Officiating replay system

[edit]

In 2013, ICC tested a broadcaster-free replay system. Under the experiment, a non-match umpire sits in a separate room with a giant monitor and has discretion over which replays to see rather than relying on the broadcaster. The non-match umpire mirrors the role of the third umpire without having the duty of making adjudications. The system was first used in an Ashes Test (where Nigel Llong performed the duties of non-match umpire) and was repeated in a Pakistan-Sri Lanka ODI.[53]

After The Ashes in 2013, the ICC has started to take steps to give third umpire access to instant replays. This is regardless of calls being referred to by on-field umpires. By doing so, ICC wants to make sure that any obvious mistakes are avoided in future.[54]

Reception

[edit]

The Decision Review System has generally received positive response from players and coaches since its launch. Because of its positive response, the ICC has attempted to apply uniform application of DRS in all cricket games around the world, but this has been difficult for some countries to implement. Some countries, especially the poorer ones, are unable to afford the technology and choose to use parts of it or not use it at all.[55] The technology is often used by broadcasters to bring an even more vivid analysis of specific plays and games. It was designed to eradicate the errors of umpires, and it has done so in many games.

However, there have been some negative responses to the DRS technology as well. West Indies legend Joel Garner labelled the system a "gimmick".[56] Another West Indian Ramnaresh Sarwan said that he was not a supporter of the experimental referral system.[57] Former umpire Dickie Bird also criticised the system, saying it undermines the authority of on-field umpires.[58] The BCCI has expressed a skeptical view on the adoption of the system if it is near perfect.[59] Pakistani spinner Saeed Ajmal expressed dissatisfaction over the Decision Review System after a semi-final of the 2011 Cricket World Cup against India. He said that DRS showed the line of the ball deviating more than it actually did.[60] Hawk-Eye officials admitted in December 2014 that their review technology made an error in a decision to give Pakistan opener Shan Masood out in the second Test against New Zealand in Dubai (17-21 November 2014). At a meeting held at the ICC office in Dubai two weeks later, Hawk-Eye is understood to have conceded to Pakistan captain Misbah-ul-Haq and team manager Moin Khan that the projection used by their technology for the Leg before wicket decision was incorrect.[61] Also, a challenge can only be made by the captain within a 15-second window from when an initial decision is made, but it can be lengthened if no clear decision is made, especially they are assumed not out if there is no reaction by the umpire.

During the 2012/2013 domestic season Cricket Australia trialed a review system in the domestic one day competition where the third umpire could intervene and review any out or not out decision. The review system was unpopular among players and critics, which the Australian International Twenty20 captain George Bailey calling the system "shocking and embarrassing".[62] The review system was dropped by Cricket Australia after only two rounds of the competition.[63]

During an ODI between Australia and South Africa in June 2016, Hawk-Eye's accuracy came under criticism after AB de Villiers was dismissed clean bowled by Josh Hazlewood but subsequent Hawk-Eye trajectory prediction of the same delivery showed that the ball would go over the stumps.[64]

Player Review statistics

[edit]

An analysis of more than 2,100 Player Reviews between September 2009 and March 2017 found that:[65][66]

  • 26% of Player Reviews resulted in on-field decisions being overturned.
  • Reviews by batsmen were less frequent than reviews by bowling teams, as 41% of reviews were by batsmen and 59% by bowling teams.
  • Reviews by batsmen were more likely to be successful, with a 34% success rate, compared to a success rate of about 20% for bowling teams.
  • 74% of referrals were for LBW, 18% for wicketkeeper catches, and the rest for catches elsewhere or indeterminate reason. The success rate was only 22% for LBW, compared to 40% for wicketkeeper catches.
  • There were on average about 1.4 batting overturns and 1.2 bowling overturns per match. Initial fears that DRS would bring an increase in the number of dismissals have, therefore, not come true.
  • The DRS claims to have 90% accuracy [67]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
The Decision Review System (DRS) is a technology-based protocol in that enables on-field umpires and players to challenge and verify contentious umpiring decisions, particularly regarding dismissals such as leg before wicket (LBW), caught behind, and , through referrals to a utilizing advanced video and tracking tools. Introduced to minimize and enhance the fairness of the game, the DRS originated from earlier third-umpire referral systems using basic TV replays, but evolved into a comprehensive setup following trials in the 2008 Test series between and . The (ICC) began requiring its use in international matches from 2009 where technology was available, though adoption was gradual due to ongoing debates over cost, accuracy, and mandatory status. Over time, refinements have included protocol updates, such as the elimination of review top-ups after 80 overs in Tests in 2017 and the introduction of DRS in T20 Internationals that same year. More recent updates in June 2025 refined protocols for reviewing multiple simultaneous appeals in sequence and other decision alignments. At its core, the DRS operates via player-initiated or umpire-initiated reviews: a captain or batter signals disagreement with an on-field call within 15 seconds, prompting the third umpire to analyze footage and data before relaying a final verdict back to the field. Key technologies include for predicting ball trajectories in LBW scenarios, UltraEdge (an advanced snickometer using directional microphones) for detecting bat-pad contact via sound spikes, ultra-motion cameras for visual confirmation of edges or catches, and occasionally thermal imaging like for heat signatures, though the latter has been phased out in some competitions due to reliability concerns. Under ICC regulations, the number of unsuccessful player reviews is limited per —typically three in matches, two in One Day Internationals (ODIs), and two in (T20) matches—to prevent overuse, with reviews not lost if an umpire's call on marginal projections (where the ball clips the stumps but is inconclusive) upholds the original decision. Only dismissal decisions are reviewable by players, while umpires can consult the third freely for non-reviewable incidents like boundary calls or run-outs; all protocols are detailed in competition-specific appendices to ensure consistency across global events.

History

Origins and Development

The Decision Review System (DRS) was conceived in the early 2000s by the as a response to growing concerns over high-profile umpiring errors that undermined the game's integrity. A pivotal catalyst was the , where controversial (lbw) decisions, such as those dismissing Australian captain and despite apparent inside edges off English bowlers, drew widespread criticism and calls for technological intervention. These incidents, officiated by umpires including , highlighted the limitations of human judgment in complex scenarios, prompting the to explore referral mechanisms to the third umpire using video evidence. Central to DRS's development was the ball-tracking technology, invented by British engineer Paul Hawkins in 2001 while working at Roke Manor Research. Initially designed for enhancing television broadcasts of by predicting ball trajectories, Hawk-Eye used multiple high-speed cameras to triangulate the ball's path and simulate its continuation toward the stumps. By 2006, the system had been refined for potential umpiring applications, building on its successful integration into coverage since its debut in a 2001 Test match between and . This adaptation laid the technological foundation for DRS, shifting from mere visualization to decision-making support. Early trials of referral systems began with the in , marking the first experimental use of technology in an international context. Umpires were allowed to consult the third umpire for lbw decisions using and slow-motion replays, though the trial revealed technical limitations and inconsistent application, leading to mixed feedback. These experiments helped refine protocols, emphasizing limited referrals to avoid disrupting game flow. Key milestones included the ICC's 2007 discussions on standardizing limited player reviews, culminating in a formal proposal for a structured system. This paved the way for the first official Test match implementation in July 2008 during the versus series in , where DRS was trialed with , sound-based , and video replays. The debut featured 11 successful reviews by and one by , though glitches like delayed graphics underscored ongoing development needs; Virender Sehwag's lbw dismissal became the first overturned via player review. Later enhancements, such as UltraEdge for , built on these foundations without altering core mechanics.

Implementation in Cricket Formats

The Decision Review System (DRS) debuted in Test cricket during the first Test match between and in in July 2008, marking the first official trial of the technology in international play. This initial implementation was limited to that three-match series, where it was used to review close decisions, including the first successful overturn of an on-field umpire's call involving Indian opener . Following positive feedback from the trial, the (ICC) gradually expanded DRS usage, mandating its application in all Test matches by June 2011 to standardize decision-making across the format. Adoption in One Day Internationals (ODIs) began with its first use in January 2011 during England's tour of ODI series, initially as an optional tool subject to bilateral agreements between boards. The ICC formalized its role by mandating DRS for the , where it was employed across all matches to ensure consistency in high-stakes encounters, with ball-tracking available universally and additional technologies like on a selective basis. For Internationals (T20Is), DRS rollout lagged behind, with the first implementation occurring in October 2017 during the ICC Women's World T20, though recommendations for its use in men's T20 series were discussed as early as 2011; further refinements in 2017 included its introduction in men's T20Is and the elimination of review top-ups after 80 overs in Tests. Variations in implementation arose due to financial and logistical differences among host boards, most notably the Board of Control for Cricket in (BCCI), which resisted DRS in matches hosted in until November 2016, citing concerns over technology accuracy and costs exceeding $50,000 per day. In 2013, the ICC shifted policy to place the onus on host boards for funding and deciding DRS usage in bilateral series, aiming to promote wider adoption without universal mandates amid ongoing debates. This approach allowed flexibility, such as modified setups excluding certain technologies to reduce expenses. As of 2025, DRS has been integrated into since the , where it was used for the first time across televised matches to enhance fairness in the format. In bilateral series, hybrid models—employing partial DRS components like basic ball-tracking without full imaging—continue to be adopted for cost-saving purposes, particularly in non-ICC events where full implementation could strain smaller boards' budgets.

Technological Components

Ball-Tracking Systems

Ball-tracking systems form a of the Decision Review System (DRS) in , primarily enabling predictions of the ball's trajectory for (LBW) decisions and aiding in catch validations by modeling the ball's path. These technologies capture the ball's flight from release to potential impact, extrapolating post-bounce behavior using physical simulations of spin, swing, and seam movement influenced by pitch conditions. The predominant system, , utilizes six high-speed cameras—typically operating at 100 frames per second—strategically placed around the field to triangulate the ball's position in three dimensions throughout its journey. Developed by Hawk-Eye Innovations, it generates predictive trajectories by applying laws of physics to account for variables such as ball spin and environmental factors, producing immersive 3D visualizations for umpires and broadcasters. The system claims an overall decision accuracy of 99%, with a mean positioning error of about 2.2 mm, allowing for precise determination of whether the ball would have hit the stumps. Alternative ball-tracking technologies include Virtual Eye, a camera-based system operated by Animation Research Limited, which employs similar multi-angle tracking and has been used in international broadcasts and some DRS implementations, particularly in and . Unlike radar-dependent systems explored in other sports, cricket's primary alternatives remain optical, with predictive algorithms calibrated to handle pitch degradation and atmospheric effects like humidity-induced swing. Prior to each match, these systems undergo rigorous calibration, involving operators tracking 20-30 practice deliveries to align cameras with the field dimensions and verify ball detection algorithms, achieving error margins below 5 mm at the point of predicted impact. This setup ensures reliability across varying conditions, such as grass type or levels affecting bounce. Since its ICC approval in 2008, has evolved with AI integrations by 2023, enhancing real-time trajectory adjustments for dynamic factors like and , improving predictive fidelity in diverse global venues. These advancements build on foundational physics models, reducing human operator input while maintaining the system's core optical tracking.

Edge Detection Technologies

Edge detection technologies in the Decision Review System (DRS) are specialized tools designed to verify whether the cricket ball has made contact with the or pad, particularly for close calls such as behind or bat-pad decisions. These systems analyze audio, visual, and data to detect faint edges that may not be visible to the or audible to umpires. Primarily, they include sound-based methods like UltraEdge and imaging like , which work in tandem with other DRS components to provide third umpires with objective evidence. Although trialed and used in some international series, is not a mandatory component of ICC DRS protocols as of 2025 and has been largely replaced by sound-based systems in major events. UltraEdge, also known as Real-Time Snicko or RTM, is a prominent sound-based technology that combines audio analysis from stump with visual patterns to identify edges. It detects spikes in sound waves corresponding to ball contact, distinguishing them from ambient noise by synchronizing audio with high-speed video footage. Developed as an advancement over the original , Real-Time Snicko was introduced for official DRS use around 2013, enabling near-real-time processing for faster reviews. The uses directional placed near the stumps to capture subtle vibrations, producing a graphical overlay that highlights potential contacts. Sound-based alternatives, including spike analysis from multiple , achieve accuracy rates of approximately 95% for audible snicks, making them reliable for confirming edges in most conditions. Hot Spot employs infrared thermal imaging to capture heat signatures generated by friction when the ball strikes the bat or pad, producing a visual "hot spot" on the equipment. This technology requires pairs of high-resolution infrared cameras positioned at strategic angles around the field to detect temperature changes as small as 0.01 degrees Celsius. While effective in dry environments, Hot Spot has faced reliability challenges in humid conditions, where sweat and moisture can create false positives or obscure genuine marks, leading to its phased out or reduced use in some venues by 2020. As a result, many international matches now prioritize sound-based systems over thermal imaging for consistency. Recent advancements have integrated enhanced AI filtering into UltraEdge to minimize false positives, particularly from non-contact sounds like clothing rubs or pad noises. Machine learning algorithms now process audio data to better isolate relevant spikes, improving decision accuracy in complex scenarios.

Review Process

The Decision Review System (DRS) review process begins when a batter, for an "out" decision, or the fielding captain, for a "not out" decision, signals a request by forming a "T" shape with their arms at head height within 15 seconds of the on-field umpire's call. The on-field umpires then refer the decision to the third umpire, who analyzes TV replays and technological aids to determine its accuracy. Reviewable dismissal decisions include leg before wicket (LBW), caught, bowled, stumped, hit wicket, and run out. Non-reviewable decisions include timed out and certain other non-dismissal calls, such as fair catches that are not contentious. If the review overturns the on-field decision, it is successful, and the team retains its review allocation; if unsuccessful, the team loses the review; however, if the decision stands due to an umpire's call on impact or projection in LBW cases, the review is typically retained.

Umpire Reviews

In the Decision Review System (DRS), reviews enable on-field s to consult the third for clarification on specific decisions without player involvement, ensuring efficient resolution of uncertain calls. These reviews are used for certain scenarios, such as run-outs at the non-striker's end and boundary catches where the on-field umpires cannot definitively determine if the ball touched the ground or the boundary . Discretionary referrals are permitted for close stumping decisions or other visual ambiguities, like whether a batter is or hit , allowing the third to examine replays for confirmation. The protocol for initiating an umpire review involves the on-field umpire signaling by crossing their arms to form a television screen shape, prompting immediate consultation with the third umpire. The third umpire then analyzes available footage from multiple camera angles, typically completing the review in 30 to 60 seconds, and relays the verdict via earpiece to the on-field umpires for announcement. This process prioritizes speed to minimize disruptions while relying on visual evidence alone, excluding technologies for non-visual assessments. The scope of these reviews is confined to objective visual verification, such as confirming contact with the ball or ground in . Prior to mid-2020, subjective judgments like front-foot were not technologically assisted in umpire reviews, leaving them to on-field assessment; however, from October 2020, the third umpire began checking validity for dismissals using side-on replays to enhance accuracy. Additionally, soft signals—preliminary "out" or "not out" judgments by on-field umpires for catch referrals—were required until June 2023, when the ICC eliminated them to avoid influencing the third umpire's independent analysis based on clear evidence. A notable instance of umpire reviews occurred during the 2019 ICC Cricket World Cup final between and , where consultations resolved critical boundary decisions, including deflections near the rope that determined six versus five runs, contributing to the match's dramatic tie.

Player Reviews

In the Decision Review System (DRS), player reviews allow the batting or fielding team to challenge an on-field 's decision regarding a dismissal. The batter initiates a review for an "out" decision, or the fielding captain for a "not out" decision, by forming a T-shape with their arms, which must occur within 15 seconds of the umpire's call to ensure timely challenges. This process applies specifically to potential dismissals such as (LBW), caught behind, or , enabling teams to seek clarification on contentious calls without disrupting the game's flow. Effective June 2025, for caught dismissals, if no bat contact is detected, the will also check for LBW if applicable; additionally, if the original decision stands solely due to an umpire's call (on impact or projection), the review is not considered unsuccessful and does not count toward the limit. Once signaled, the Third Umpire takes over, conducting a thorough analysis of the incident using all available technological aids, including ball-tracking for trajectory predictions and edge-detection systems like UltraEdge or Snicko for sound-based confirmations of contact. For incidents involving multiple possible dismissals (e.g., LBW followed by ), the third umpire reviews them in chronological order. The on-field umpires then view the graphical evidence on a monitor before announcing the final call. This structured assessment contrasts with umpire-initiated reviews, which are automatic for certain close calls and do not involve team input. Prior to 2023, the on-field umpire was required to provide a "soft signal" indicating their initial view (out or not out) when referring a caught dismissal to the Third Umpire, a practice intended to guide the process but criticized for introducing bias. The abolished the soft signal effective June 1, 2023, as part of updated DRS protocols, aiming to eliminate subconscious influences and promote more objective technology-driven verdicts. This change has been credited with enhancing fairness in high-stakes matches, though it requires umpires to rely solely on video and audio evidence without preconceived notions. A notable early example of player reviews in action occurred during the July 2008 first Test between and at , where Sri Lankan batter became the first player dismissed via DRS (). Such incidents underscored the strategic value of player s, influencing teams to integrate DRS assessments into their tactical decision-making.

Decision Finalization

The third evaluates the review using available technologies and footage, overturning the on-field 's decision only if there is clear evidence that it was incorrect; if the evidence is inconclusive, the original on-field decision stands. Effective June 2025, if a decision remains unchanged solely due to an 's call in LBW projections or impact, the reviewing team retains the review. This criterion ensures that technology supports rather than overrides human judgment without definitive proof. Upon reaching a conclusion, the third communicates the outcome to the on-field umpires via using standardized protocol phrases, such as "the original decision is correct" or "you can change your decision" to out or as applicable. The on-field then signals the final decision to the players with the appropriate , while graphical visualizations of the —such as ball-tracking paths or edge waveforms—are displayed on the stadium's big screen for transparency to spectators. To maintain game flow, DRS reviews are typically completed quickly, with guidelines introduced in ICC playing conditions to minimize delays, such as shortening standard protocols when outcomes are quickly evident. Following finalization, no additional challenges can be initiated on the same delivery, rendering the decision binding for that incident.

Rules and Protocols

Review Allocations

In Test matches, each team is allocated three unsuccessful reviews per . Successful reviews, where the on-field decision is overturned, do not count against this quota, allowing teams to retain their full allocation for subsequent challenges. This structure was updated in the era to three reviews, aiming to minimize errors amid challenges with umpire experience. In limited-overs formats, teams are permitted two unsuccessful reviews per innings in One Day Internationals (ODIs) and one unsuccessful review per innings in Internationals (T20Is). These allocations are typically per team rather than shared, though certain bilateral series or tournaments may adjust protocols for balance. The limit encourages judicious use, as reviews are often reserved for high-stakes dismissals like lbw or decisions. A failed review—where the third umpire upholds the on-field decision—results in the permanent loss of one from the team's quota for that . There is no provision for carry-over of unused or regained reviews to subsequent or the second of the , preventing accumulation and promoting match-long decision-making discipline. This consequence underscores the risk-reward dynamic of the system, as teams must weigh potential gains against quota depletion. While international matches follow these standardized limits, domestic competitions exhibit variations to suit logistical or financial constraints; for instance, the operates with two reviews per . The (ICC) formalized uniform DRS protocols across formats in , eliminating prior inconsistencies like the 80-over top-up in Tests and mandating consistent allocations to ensure equity in global events.

Umpire's Call and Margins

The umpire's call is a protocol within the Decision Review System (DRS) specifically for (LBW) decisions, where ball-tracking indicates a marginal outcome such that the on-field umpire's original decision is upheld. This occurs if the projected path of the ball is predicted to hit any part of the stumps but the point of impact or is deemed marginal. The rule accounts for the predictive uncertainties in ball-tracking, preventing from overriding umpires in extremely close scenarios. For LBW reviews, the margins are visualized through ball-tracking graphics, which display the and ; the ball must be to hit more than 50% of the stumps to overturn a not-out decision definitively, with scenarios where the projection shows the ball clipping the stumps triggering the umpire's call if the original decision is not clearly wrong. These thresholds reflect the diameter of the (approximately 7.2 cm) and the technology's resolution limits. The 3D projections briefly reference ball-tracking visuals for clarity during broadcasts. In June 2025, the ICC updated the zone to the precise outline of the stumps and bails to improve projection accuracy. The rationale for the 's call lies in balancing technological constraints with human expertise, as predictive models cannot guarantee absolute precision due to variables like ball spin and atmospheric conditions. It applies solely to LBW dismissals, excluding decisions or run-outs, to preserve umpire authority in subjective judgments while correcting egregious errors. Hawk-Eye's validated accuracy is within 5 mm for initial contact but widens for projections, justifying the buffer to avoid unjust overturns.

Usage and Impact

Statistical Overview

Since its introduction, the Decision Review System (DRS) has been employed in approximately 15% of dismissals across Test matches from 2010 to 2020, according to aggregated data from international fixtures. Success rates for overturns typically range between 26% and 35% overall, with batsmen achieving higher rates (around 34-37%) compared to bowling sides (20-22%), primarily due to the higher volume of close calls on dismissals like LBW. Usage varies by format, with longer games seeing more frequent reviews; pre-2020 data indicates roughly 25% of dismissals reviewed in ODIs versus about 10% in T20Is, reflecting the limited review allocations (one per in T20Is, two per in ODIs, versus three per in Tests with resets). This disparity underscores DRS's greater tactical role in endurance formats, where teams average 2-3 reviews per . The system's impact on match outcomes is evident in its correction of umpiring errors, with analyses showing an overall reduction of around 80% in contested decisions through technology-assisted reviews; for instance, CricViz data highlights improved accuracy from pre-DRS levels of 85-90% to over 98% in reviewed cases post-2010. In the , DRS overturns influenced key moments, contributing to altered momentum in a drawn series. Trends show an increase in successful LBW overturns following the 2021 ICC refinement to the DRS wicket zone, which extended tracking to the top of the bails and raised the baseline overturn rate for non-umpire's call LBWs from 22% to 27%, enhancing precision in marginal projections. This adjustment has led to more consistent outcomes, with LBW dismissals rising to 16.6% of total wickets in the DRS era from 14% pre-DRS. In June 2025, the ICC further refined DRS protocols, updating the zone to the precise outline of the stumps and bails for greater accuracy in projections, and introducing secondary review processes for dismissals involving potential no-balls alongside caught behind or LBW decisions. These changes aim to further minimize ambiguities in real-time decision-making across formats.

Reception and Controversies

The Decision Review System (DRS) has received widespread praise from the (ICC) for promoting fairness and significantly reducing umpiring errors in matches. ICC assessments have highlighted how DRS corrects a substantial portion of on-field mistakes, with one evaluation noting that it rectified four out of seven errors in a single Test match. Elite umpire has echoed this sentiment, emphasizing the system's role in minimizing human judgment lapses, as seen in ICC endorsements of his decisions in high-stakes games. By 2025, DRS adoption has become nearly universal across , with enhancements like upgrades for faster accuracy and expansions to cover no-balls and wides in leagues such as the IPL, though isolated exceptions persist in cost-constrained tournaments like the PSL. Despite its benefits, DRS has faced criticisms for technological glitches, particularly with the imaging system, which repeatedly failed to detect faint edges during the 2011 England tour of and the . In one notable instance, missed an edge from on multiple occasions, leading to ongoing debates about its reliability in humid or low-light conditions. Additionally, the high costs of implementation—estimated at $15,000–$16,000 per day or up to $60,000 per match—pose significant barriers for smaller cricket boards, limiting access in lower-profile series and prompting calls for ICC subsidies to ensure equity. Key controversies have underscored these issues, including the 2019 ICC Cricket World Cup semi-final between and , where Virat Kohli's LBW dismissal sparked outrage due to the ball-tracking projection clipping the bails by a under umpire's call, while a similar decision for England's earlier in the tournament was overturned, highlighting perceived inconsistencies in DRS application. In 2024, debates intensified around AI integration into DRS, with concerns raised about potential biases in machine learning algorithms that could favor certain playing styles or conditions, as explored in analyses of technology's role in decision-making. Studies have provided mixed but generally supportive insights into DRS's impact, with the Cricket Board's (ECB) 2022 DRS Regulations emphasizing the system's enhancement of confidence by requiring a "high degree of confidence" for overturning decisions, thereby reducing second-guessing on the field. Ongoing discussions advocate for full automation, proposing AI-driven systems to eliminate 's call ambiguities and human biases, as outlined in research on for third- decisions, though experts caution that a hybrid human-AI model remains more feasible in the near term.

References

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