How DRS Works in Cricket: Ball-Tracking, Edges and Umpire’s Call
The Decision Review System, or DRS, lets players challenge an on-field umpire’s decision using technology. It has changed how cricket is played and watched, but it also confuses many fans. Why does a ball that looks like it is hitting the stumps stay “not out”? What does “umpire’s call” really mean? This guide explains how DRS works in clear steps.
What DRS is for
DRS exists to correct clear mistakes, not to re-umpire every close call. When a player asks for a review, the decision goes to the third umpire, who watches replays and technology and then tells the on-field umpire whether to keep or change the decision. The original decision stays unless the evidence clearly shows it was wrong.
How a review is requested
The batter who is given out, or the fielding captain when a not-out decision is given, makes a “T” sign with their arms. They must do this within a short time limit after the decision, usually around 15 seconds. Each team has a limited number of unsuccessful reviews per innings, set by the playing conditions of the match. A review that overturns the decision is kept, and in most cases a review that ends in “umpire’s call” is also kept.
The technology the third umpire uses
- Replays from multiple cameras, including slow motion and front-on views, to check catches, stumpings, run-outs and no-balls.
- Edge detection, such as an audio-based “snickometer” or UltraEdge, which shows a spike when the ball touches the bat or glove.
- Hot Spot, used in some series, which shows heat marks where the ball made contact.
- Ball-tracking, such as Hawk-Eye, which shows where the ball pitched, where it hit the pad, and predicts whether it would have hit the stumps.
Reviewing an lbw decision step by step
For leg before wicket, the third umpire checks three things in order. First, did the ball pitch in line, or outside leg stump? A ball pitching outside leg cannot result in lbw. Second, was the impact on the pad in line with the stumps? An impact outside off stump only counts if the batter made no genuine attempt to play the ball. Third, would the ball have gone on to hit the stumps? If any one of these says not out, the batter is not out. The third umpire also checks for a no-ball and for any bat contact before the pad.
Umpire’s call explained
Ball-tracking is a prediction, so it has a margin of error. To respect that, the system uses a zone. If the predicted path shows the ball only clipping the stumps, rather than hitting them clearly, the original on-field decision stands. That is umpire’s call. It means the same delivery can be out if the umpire gave it out and not out if the umpire gave it not out. Fans find it frustrating, but it keeps the human decision central when technology cannot be certain.
Why DRS differs between matches
DRS is not available everywhere. Major international matches and top franchise leagues usually have it, while many domestic games do not, because the cameras and tracking systems are expensive. The number of reviews and some details can also vary by format and competition. If you want to see how playing conditions change across formats, this guide to format-by-format rule differences sets them side by side.
Smart use of reviews
Captains treat reviews as a resource. Using one on a speculative appeal early in an innings can leave a team without a review when a clear mistake happens later. Batters are often advised to review only when they are confident, such as when they know they hit the ball before it struck the pad. The best teams talk quickly: the bowler, the wicketkeeper and the captain each see the ball from a different angle.
Summary
DRS sends a disputed decision to the third umpire, who uses replays, edge detection and ball-tracking. For lbw, pitching, impact and hitting the stumps are checked in order, and umpire’s call protects the on-field decision when the margin is too small to be sure. For more clear explanations of cricket rules and match situations, visit 9Wicket Cricket.