Third Umpire and Technology: How DRS Changed Cricket
The Decision Review System (DRS) introduced Hawk-Eye ball tracking, Hotspot, and Snicko to cricket umpiring, allowing teams to challenge on-field decisions. This guide explains what DRS includes, how each technology works, the review process, and what DRS can and cannot do.
The Decision Review System (DRS) is cricket's technology-assisted review system allowing players to challenge on-field umpiring decisions. Introduced in Test cricket in 2009 (some nations objecting until 2016 when India finally adopted it), DRS uses multiple technologies working together: Hawk-Eye (or equivalent ball-tracking), Hotspot (thermal imaging), Real-Time Snicko (audio spike detection), and Ultra-Edge. Each technology addresses specific uncertainty areas in umpiring — tracking where a delivery pitches, detecting bat/pad edges, and projecting where a ball would have gone.
Hawk-Eye Ball Tracking
Hawk-Eye reconstructs the ball's trajectory using multiple high-speed cameras positioned around the ground. For LBW decisions, it projects where the ball would have travelled after striking the batsman (assuming the batsman's leg wasn't there). The projection is the most controversial aspect of DRS — the projection further from impact carries increasing uncertainty, which is why the 'umpire's call' zone exists for balls hitting the wicket or near the stumps. If any part of the projected ball clips the stumps, it's out; if the ball is 'umpire's call' on whether it would hit the stumps, the on-field umpire's original decision stands.
Hotspot and Snicko
Hotspot uses infrared cameras to detect heat generated by friction when ball meets bat or pad — producing a bright white patch where contact occurred. Its limitation: it requires friction to generate heat, so a thin inside edge (glancing contact) may not show. Snicko/Ultra-Edge detects audio spikes in the stump microphone at the moment a potential edge occurs, correlating the spike timing with the frame of ball-bat proximity on video. Together they help determine edges — whether the ball touched bat (caught behind, LBW review). Neither is perfect alone; broadcast analysts typically use both.
The Review Process
Each team gets 2 unsuccessful DRS reviews per innings in Tests (1 per innings in T20Is and ODIs). Reviews are retained if the on-field decision is changed ('successful' review). The review process: the fielding or batting team's captain signals immediately (within 15 seconds); the third umpire examines each relevant technology; if the original decision is overturned, no review is lost; if confirmed, the team loses one review. Reviews encourage umpires to make decisions without fear of being wrong — knowing technology will catch clear errors.
Frequently asked questions
How many DRS reviews does each team get per innings?
Each team gets 2 unsuccessful DRS reviews per innings in Test cricket, and 1 unsuccessful review per innings in ODIs and T20Is. A review is 'unsuccessful' if the third umpire upholds the on-field decision. If the on-field decision is overturned (a successful review), the team retains their review. Reviews reset at the start of each innings.
What is Hawk-Eye in DRS?
Hawk-Eye is the ball-tracking technology used in DRS to reconstruct the delivery's path and project where it would have gone after striking the batsman. It uses multiple high-speed cameras to calculate the ball trajectory. For LBW decisions, it projects whether the ball would have hit the stumps. Decisions in the 'umpire's call' zone (marginal projections) retain the on-field umpire's original decision.
What is umpire's call in cricket?
Umpire's call is the DRS rule that where a decision is marginal — particularly where the ball-tracking projection shows the ball hitting the edge of the stumps or impact is on the line of the crease — the on-field umpire's original decision stands. It was introduced because ball-tracking projection carries inherent uncertainty farther from impact, and DRS should only override clear errors, not marginal calls. A review involving 'umpire's call' is not lost if the overall decision is upheld.