Umpire Decision Review System

The Umpire Decision Review System (abbreviated as UDRS or DRS) is a technology-based system used in the sport of cricket. The system was first introduced in Test cricket, for the sole purpose of reviewing controversial decisions made by the on-field umpires as to whether or not a batsman had been dismissed. The system was first tested in an India v Sri Lanka match in 2008, and was officially launched by the International Cricket Council (ICC) on 24 November 2009 during the first Test match between New Zealand and Pakistan at the University Oval in Dunedin. It was first used in One Day Internationals (ODI) in January 2011, during England'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 in an innings.

In February 2017 the ICC agreed the use for all future ICC World Twenty20 tournaments, with one review per team. The first T20 tournament scheduled to use the technology will be the 2018 ICC Women's World Twenty20.

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