Decision Review System
The Decision Review System 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, and players may request that the third umpire consider a decision of the on-field umpires.
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 in January 2011, and used in a Twenty20 International in October 2017.
History
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.
The Player Referral system was first tested in an India v. Sri Lanka match in 2008, and was officially launched by the International Cricket Council on 24 November 2009, during the first Test between New Zealand and Pakistan at the University Oval in Dunedin. It was first used in One Day Internationals in January 2011 during Zimbabwe's tour of Australia. The ICC initially made the UDRS mandatory in all international matches, 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.
In October 2012, the ICC made amendments on lbw protocols, increasing the margin of uncertainty when the ball hits the batsman's pad. In July 2016, the rules were amended once again, reducing the margin of uncertainty. The updated rules were first used in the ODI match between Ireland and South Africa in September 2016.
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.
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.
In February 2013, the ICC agreed the use for all future ICC World Twenty20 tournaments, with one review per team. The first T20 tournament to use the technology was the 2018 ICC Women's World Twenty20. 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.
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" 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.
From 1 June 2023, the "soft-signal" requirement for umpires when referring catches was scrapped as they were "unnecessary and at times confusing".
Components
The components of DRS are:- Video replays, including slow motion.
- Hawk-Eye, or Virtual 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 or Ultra-Edge : 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. RTS is calibrated each morning without needing manual syncing during play. 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.
- 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. The system came under fire after the 2013 Ashes in England. It was claimed that using silicone tape prevented faint edges being picked by Hot Spot, which was later confirmed by a MIT report.
| System | No. of cameras | Camera framerate |
| Hawk-Eye | 6 | 340 fps |
| Virtual Eye | 4 | 230 fps |
System
Umpire reviews
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:- 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.
- 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.
The on-field umpires may also request the Third Umpire reviews the following:
- Boundary calls. 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.
Player reviews
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, 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. 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. 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.
Umpire's call
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".
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.
If either impact or wickets is judged umpires call. The umpire's original decision is upheld and the reviewing team retains their review.
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 which are perceived to be unfairly decided by forensic and technical means.
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.