Video Review

Overview

Video review — also called instant replay, a challenge, or a referral system — is an officiating aid in which officials look again at recorded footage of a contested moment before a decision is finalized. On-field officials make calls in real time with the naked eye and can miss events that are fast, screened, or bunched together. A review supplements that live judgment: it may be started by the officials themselves, by a dedicated off-field video official watching monitors, or by a team spending one of a limited number of challenges. The purpose is to correct clear mistakes on decisions that materially affect the contest — whether a ball crossed a line, landed in or out, whether a player was offside, whether contact was a foul, or whether a score should stand.

The mechanics differ by sport but the structure is shared: a defined set of reviewable situations, a threshold for overturning, and a protocol for pausing play, consulting the footage, and announcing the outcome. Many systems keep the original call unless replay shows a clear and obvious error, so the live decision keeps priority when the evidence is inconclusive. Reviews draw on multiple synchronized camera angles and slow motion, and for boundary or line calls an automated ball-tracking or goal-line system can supply a near-instant objective answer. Because every stoppage costs time and momentum, most implementations cap how much can be reviewed and how often, trading a small loss of flow for greater accuracy on the calls that matter most.

What it involves

Trigger routes vary: officials may call for a review themselves, a dedicated video official may flag a check from the monitors, or a team may formally challenge or refer a decision using a limited allowance that is often kept when the challenge succeeds.
An overturn usually requires a clear and obvious error, so an inconclusive replay leaves the on-field call standing — a deliberate design choice that preserves the primacy of the live decision.
Only certain situations are reviewable, typically boundary and line calls (in or out, ball over the line), scoring plays (score or no score, the value of a score), and serious infractions or misconduct — not every routine decision.
Reviews rely on multiple camera angles and slow motion; for line and boundary questions, sensor-based or ball-tracking technology can give an automated, near-instant verdict independent of camera framing.
Rules cap the number of reviews, restrict which moments qualify, and often set time limits, balancing accuracy against the flow, rhythm, and pace of the game.