DRS in Cricket: How the Decision Review System Works
The Decision Review System (DRS) has transformed cricket umpiring. This guide explains how DRS works, what technologies it uses, and how teams should use their reviews strategically.
The Decision Review System was introduced by the ICC in 2008 to reduce howler decisions in international cricket. Teams can challenge on-field decisions using a combination of technologies — ball tracking, edge detection and ball-impact reconstruction — that together provide a comprehensive picture of what actually happened. DRS has transformed the game, reducing clear umpiring errors dramatically, though 'umpire's call' marginal decisions remain controversial.
How Many Reviews Does Each Team Get?
In Test cricket, each team has two unsuccessful reviews per innings. An unsuccessful review is one where the on-field decision is upheld — the review system confirms the umpire was right. If a team's review succeeds (the decision is overturned), they retain that review. In ODIs and T20Is, each team has one review per innings. Reviews reset at each innings and, in Tests, also reset after 80 overs of play.
The Technologies Used
DRS combines three technologies: ball tracking (Hawk-Eye or Vantage) predicts the ball's trajectory if uninterrupted; Ultra Edge (or similar) uses microphones and visual synchronisation to detect whether the ball contacted the bat; and ball-impact reconstruction shows exactly where on the bat or pad the ball struck. Together, these answer the three LBW questions: did it pitch outside leg? did it hit the bat? would it have hit the stumps?
Strategic Use of Reviews
Teams use reviews most effectively by challenging clearly wrong decisions immediately — the batter or captain sees the ball land outside leg stump, or the fielding side sees no edge on the bat. Reviews wasted on dubious LBW decisions or marginal catches are not available for genuine howlers later in the innings. Some teams track review success rates across matches to identify which types of decisions are most overturnable.
Frequently asked questions
When can a team not use DRS?
DRS is only mandatory at the top level of ICC events when the full technology package is available. In Tests at grounds without the required camera setup or ball-tracking system, DRS is not available. Many bilateral series below ICC event level also do not use the full DRS system.
Can the third umpire initiate a review without a team referral?
Yes — in certain situations. A front-foot no-ball check (for the bowling crease front-foot position) is done automatically by the third umpire on every delivery in most ICC events since 2017, without requiring a review. The on-field umpires can also refer a catch to the third umpire without a team review request.