DRS Explained: How the Decision Review System Works
By LBW Editorial Team · learnbeyondwicket.com · August 2026 · 7 min read
The Decision Review System, commonly known as DRS, is cricket's framework for reviewing and potentially overturning on-field decisions using technology. Introduced experimentally in 2008 and now used in all ICC-sanctioned international matches, DRS has fundamentally changed the game — making umpiring more accurate, introducing new strategic considerations for captains, and creating some of cricket's most dramatic and contentious moments.
How a review works: the process step by step
When a fielding captain or batsman disagrees with an on-field umpire's decision, they have a limited time (typically 15 seconds) to signal a review by making a T-shape with their hands. The third umpire then examines the available evidence.
For a caught behind, the third umpire checks whether the ball touched the bat using audio waveform analysis and synchronised video. For an LBW appeal, the third umpire checks: was the delivery a no-ball? Did the ball pitch in line or outside leg? Did the ball hit the bat first? Was the impact in line with the stumps? And, using ball-tracking, would the ball have gone on to hit the stumps?
Review allocation: how many teams get
In Test cricket, each team starts with two unsuccessful reviews per innings. If a review is unsuccessful, the team loses one review. If the review is successful, the team retains it. Teams also regain reviews at defined points in a long Test innings.
In ODIs and T20s, allocations are smaller. The limited allocation means captains must be strategic — saving reviews for situations where they are confident the technology will reveal an error.
Umpire's call: the most controversial element
'Umpire's call' applies when ball-tracking shows the predicted path only partially overlapping with the stumps — not clearly hitting or clearly missing. In these marginal cases, the original on-field decision stands, and the reviewing team does not lose their review.
The rationale is that ball-tracking has a known margin of error, and decisions inside that margin should remain with the human umpire. Critics argue this creates inequity; supporters argue it correctly acknowledges the limits of the technology.
The technologies involved
DRS combines multiple technologies. Ball-tracking systems use cameras to track the ball's trajectory and predict its path after impact. Edge-detection systems combine audio sensors and high-speed cameras to detect contact between ball and bat. Infrared cameras detect friction heat from ball-on-bat contact, though they are not used by every broadcaster.
No single technology is used in isolation — the third umpire weighs evidence from multiple sources.
How DRS has changed team strategy
Before DRS, a batsman given out LBW had no recourse regardless of whether the decision was correct. Now, batsmen must quickly calculate the likelihood of a review succeeding. Teams coach players on DRS awareness: where the ball pitched, where it struck the pad, and whether it was heading towards the stumps.
Fielding teams make the same calculation in reverse: was the appeal strong enough to risk a review, or is this a marginal LBW where umpire's call is likely to uphold the original decision?
Conclusion
DRS has made cricket better — fairer decisions, fewer clear errors, and an additional layer of strategic thinking for captains and players. Its controversies are real but manageable, and the system continues to evolve as the technology improves.