DRS — Decision Review System Explained
A complete guide to cricket's Decision Review System (DRS) — what technology it uses, how reviews work, and strategic considerations for captains.
The Decision Review System (DRS) is cricket's technology-assisted umpiring review framework, introduced at Test level from 2009 and now used in most major international formats. DRS allows teams to challenge on-field umpiring decisions using ball-tracking, edge-detection, and ultra-motion camera technology. The system has significantly reduced incorrect decisions and added tactical depth to the game.
DRS Technologies
| Technology | What It Measures | Used For |
|---|---|---|
| Ball-Tracking (Hawkeye) | Predicted ball trajectory | LBW reviews — where the ball pitched, impact, and projected path |
| UltraEdge / Snickometer | Sound spikes when ball passes bat | Caught behind and LBW edge detection |
| Hot Spot (infrared) | Heat marks from bat-ball contact | Edge detection (not available at all venues) |
| Ultra Motion cameras | High-speed video (1000+ fps) | No-ball front foot checks, stumping decisions |
How a DRS Review Works
Each batting team has two unsuccessful reviews per innings. The fielding team is separately allocated one review per innings (in T20Is, one per innings each). When a player or fielding captain challenges a decision, the third umpire in the broadcast truck reviews the available technology evidence. For LBW reviews, all three elements must be satisfied: ball pitched in line, impact in line (or ball-tracking shows it would have hit the stumps), and the ball is projected to hit the stumps. 'Umpire's Call' applies when the impact zone or projected path marginally grazes the stumps.
Umpire's Call
When technology shows a decision is marginal — the impact or projected path of the ball is only partly hitting the stumps — 'Umpire's Call' is invoked. The original on-field decision stands, and critically, the reviewing team does not lose a review. This preserves the role of the on-field umpire for borderline decisions and acknowledges the inherent margin of error in technology predictions.
Strategic DRS Usage
DRS has added a tactical dimension to cricket. Teams must carefully manage their review allocation — wasting both reviews early can leave them unable to challenge a crucial later decision. Captains must decide quickly whether a decision looks reviewable based on their gut read plus any visual evidence. Some players are known as reliable 'reviewers' who read dismissal situations accurately; others are prone to wasting reviews on hopeless cases.
Frequently asked questions
How many DRS reviews does each team get?
In Test cricket, each team gets two unsuccessful reviews per innings. In T20 Internationals, each team typically gets one review per innings. Successful reviews do not reduce the allocation.
What is Umpire's Call in DRS?
Umpire's Call is invoked when ball-tracking technology shows the impact or projected path is only marginally on the stumps — within a defined tolerance zone. The on-field decision stands, and the reviewing team keeps their review.